texts: Why do floaters in the human eye appear to have a squiggly-line, tubular shape?

texts:
If you intentionally try not to tune out visual floaters in the eye, you can see them very clearly and they seem to have a squiggly line shape but with a volumous tubular look. Why is this?

They almost look like some kind of microbe as seen through a microscope, but that seems like a naive guess, and I'm curious to know the scientific explanation of why these entities look the way they do.


texts: what type of insect is this? is this a moth? (southeast asia - Malaysia)

texts: i found this insect in the garden behind my house a few months ago.This is the first time i saw this insect.On that day the weather is very hot.I found the insect in the afternoon.I am from Kelantan,Malaysia.The climate in Malaysia is equatorial, hot and humid, heavy rain falls in the monsoon season between november and february.


texts:
I would like to grow mushrooms on oak trees I can harvest from my property.  I've read that the best results will be when the sap is rising but the tree hasn't budded yet.  The mycelium feeds on the sugars in the logs.

I would love to be able to measure the sugar content so I could accurately asses the sugar content.  Here in Southern Oregon the winters are mild and the leafing out of the oaks varies quite a bit from year to year.

How can I measure sugar content of the sap in a tree?


texts: Why is the start of my coding sequence ATG and not TAC?

texts:
I am engineering a set of genetic sequences and have come across a surprisingly basic point of confusion that seems to have fallen through the cracks regarding coding sequences.
The standard start codon is AUG, and since this is an RNA sequence, I would thus expect that the start of the coding sequence would then be TAC, since DNA is complementary to the mRNA transcript taken from it. Wikipedia and various introductory texts confirm this expectation, e.g., in wikipedia's article on the central dogma:

The ribosome reads the mRNA triplet codons, usually beginning with an AUG

Here's another example: in the Khan academy introduction to the genetic code, the codon illustration clearly shows an AUG in the mRNA sequence.
The coding sequences that I am composing into my design, however, are all listed as starting with ATG, rather than TAC, which would be the complement of AUG. I am certain the coding sequences are not wrong, since some are very well established parts like BBa_E0040.
Something seems to have gotten confused or elided in many standard explanations, then. Why do coding sequences start with ATG and not TAC?


texts: What happens if you intake pure magnesium?

texts: We know that body needs a certain amount of magnesium. Why are magnesium supplements in the form of magnesium oxide, magnesium citrate, etc?


texts: Why is it not advisable for humans to drink distilled water?

texts:
Distilled water is pure and it does not contain any minerals, so may not be advisable for drinking.
Although laboratory made distilled water is completely pure, industry made water may still contain harmful impurities.
Also there is some probability of exosmosis into body tissues which may lead to swelling.


texts: Coalescence time: Is it different for haploids and diploids in population genetics?

texts:
I'm trying to model Cyanobacteria cells divergence in 2 populations with mutation rate $-\mu$ and I need to verify my model with a valid theory. I don't have much biology background and all the theories I can find are either valid for haploid population or mating populations. All I need to know is a theory for coalescence time/divergence for a haploid population without mating. So far I have this:

$$T = 2\times N \times d\\
D = 2 \times \mu \times T$$
in which N is the number of diploid individuals, d is the number of subpopulations (in this case 2), T is the coalescence time and D is divergence. Can I apply this to my case even though it's defined for diploid population?

Thanks


texts: What kind of caterpillar type bug is this?

texts:
I've made a photo using the reversed 58 mm lens and my cropped DSLR:

Could you please help? I really don't know where this came from.

I found it in Russia.


texts: How do Streptococcus thermophilus and Lactobacillus bulgaricus precipitate the curd of swiss cheese?

texts: I learned in my food microbiology class that Streptococcus thermophilus and Lactobacillus bulgaricus precipitate the curd of swiss cheese. However, I was wondering what type of mechanisms do these bacteria use in order to accomplish this process.


texts: I found this moth in Bengaluru/India. Its body length was nearly 2cm. Brown colored with three yellow rings.


texts:
What does the term "segregating" mean in references like the following:

"found 42% of a random sample of loci to be segregating"
"15 blood group systems are known to be segregating"


texts: Is it true that color vision is sex-linked for all species with binary sexes? Is there an evolutionary significance to the fact that color vision is X-linked in humans? E.g., only female humans can be tetrachromats.


texts: Why human cannot stand still in one place?

texts:
When a human stands in one place, he cannot stand still but we can see the body slightly swings.

Is this due to the Earth rotation or it has something with biology and muscles relaxations?

I have not been able to find a concrete documents on this thing.


texts: This was photographed near Budapest, Hungary, though my friend said she'd only ever seen these in the USA before.


texts: Why aren't we allowed to refreeze previously thawed breastmilk in refrigerator?

texts:
https://www.breastfeeding.asn.au/bf-info/breastfeeding-and-work/expressing-and-storing-breastmilk

  Previously frozen— thawed in refrigerator but not warmed

  4 hours or less (ie the next feeding)

  Store in refrigerator

  24 hours

  Do not refreeze

But in freezer the temperature is still below normal, still is there a probability of bacteria growth?

I wish to understand the reasons behind the warning. Answers with references will be appreciated.


texts: How does a biologist decide when she has enough results to publish a paper?

texts:
Biology is so exciting! Answering a question leads to  thousand more questions! There is no limit to how much one kind find out about a phenomena…

So I have always wondered how someone can decide that it is time to publish some fixed amount of research they have done. How do biologists decide when to publish a paper? How do biologists know that results are sufficient enough for a publication?


texts: How do I retrieve electronic annotation from Uniprot and GO records that relates to molecular function?

texts:
I'm interested in the endonuclease activity of the G3BP1 gene, specifically the uniprot record Q13283.

An external link guides me to UniprotKB-KW electronic annotation. How can I retrieve valuable and concrete information (e.g. catalytic sites, motifs) that explain this annotation from that link?


texts: Phosphorylation-Dephosphorylation : ATP-driven VS spontaneous

texts:
Is protein dephosphorylation most commonly spontaneous (without need of ATP)? I came across some papers that mention it, as well as the opposite case (ATP-driven), but I can't figure out which is common or which is rare.

In the case of protein phosphorylation, I would say ATP is always needed since it provides the phosphate? Or could you have a spontaneous phosphorylation using free phosphates that float around?

I am aware that in the end, pretty much everything is possible, so I am more looking for likelihood. What is commonly accepted, wide spread, and what may happen but is rare.


texts: Stem cell that can pass through blood vessel

texts:
I know that blood cells can pass through the smallest of capillaries, but I was wondering is it possible for stem cells to pass through the smallest of capillaries?

In other words, is it possible for a type of stem cell therapy where stem cells are injected into the vein in the arm for example and the stem cell would pass through into the tissue through a type of targeted therapy involving ultrasound or magnetic field.

Thank you very much ,
everyone


texts: How does menstruation proceed during one period?

texts:
I'm simplifying things here:

  A. Does a woman bleed constantly, like a drop every 10 minutes? Two hours without pad or tampon and your underwear is dirty?

or

  B. Does a woman bleed suddenly a bigger amount of menstruation fluid? Then hours might pass before it happens again?

or

  C. Both.

Might be a stupid question. I'm sorry. I read all the other information on the internet but no one answers this one for some reason. I read girls should change the pads and tampons a few times a day (like every 6 hours). Does that mean A is correct?

Thanks for any helpful information!

(Well, I guess I'm male.)

Edit:
What I want to know: If I was a woman, how would I experience the days of period bleedings? From what I read in the comments and answer(s), one should expect A (constant bleeding) and should wear pads/tampons all the time (for 2 to 7 days) and sometimes one could also experience an exceptional heavier bleeding (B)? Are there (healthy) women who would experience B most of the time? I visited Wikipedia and other random sites but they all have the other important information without answering my question. (Also I will be glad to accept an answer, which satisfies my need for knowledge.)


texts: Can bats echolocation discern what insects they are preying on?

texts: Insectivorous bats feed on many different types of insects such as mosquitoes, moths, beetles, and bees.  According to the Bat Conservation Trust, bats can discern insects from other objects but I'm having trouble finding any research saying whether bats can discern between the insects they are chasing?


texts: Which protein complex is composed of the greatest number of different kinds of proteins, and how many types are involved?

texts:
Why are some protein complexes composed of many different types of proteins? How many different types are they composed of? In particular, which protein complex has the greater number of different types of proteins in it?

For example, I've read that the ribosome consists of 70-80 different types of proteins.

How many different types of proteins are in the spliceosome for example?

I'm using the phrasing "types of proteins" to distinguish aggregates/complexes composed of many different copies of the same protein (i.e. some viral capsids) from those composed of many different kinds (i.e. ribosome, exosome complex, spliceosome).


texts: I am trying to silence the tph-1 (tryptophan hydroxylase) gene in C. elegans using the pLT63 plasmid to check if that particular gene has anything to do with the pharyneal pumping or not. Am I using the right plasmid for the purpose?


texts: What goes wrong in the immune system that leads to autoimmune diseases

texts:
As far as I understood so far, B and T cells are produced in the bone marrow, and during their maturing process in the bone marrow or Thymus, the are "programmed" to react to certain proteins. It is like giving them a particular key.

As I also understood, these "keys" are entirely created by random. Which means, that also "keys" are generated that match cells of the "host body."  Hence, if released into the bloodstream/lymph system, those B and T cells would attack the cells of the "host body."

As I understood further, there is a kind of a "security system" which checks if B and T cells are produced that would attack cells of the "host body." This security system would intervene and destroy those B and T cells before they are released into the bloodstream/lymph system.

As read lately - and I am not sure if I did understand this correctly - it is also possible, that B and T cells could also react to other cells even if the key doesn't match perfectly.

Now my questions.
Firstly, being an SW engineer interested in this topic is my understanding above correct?

Secondly, is it correct to say that autoimmune diseases are mainly caused by the following two points:
1. the "security system" in the bone marrow / Thymus failed, and therefore "bad" B and T cells were released into the bloodstream/lymph system
2. B and T cells react to other cells, even if the "key" does not match perfectly.


texts: Are SNPs or SSR copy number variation mutations more prominent?

texts:
I'm trying to get a sense of the dominant way that mutations occur.  I have seen various numbers which seem at least at first glance to conflict, and I was curious if anyone had clarification on this.
According to Shastry, "SNP alleles in human disease and evolution" (Journal of Human Genetics 47:561–566, 2002),

In two randomly selected human genomes, 99.9% of the DNA sequence is identical. The remaining 0.1% of DNA contains sequence variations. The most common type of such variation is called a single-nucleotide polymorphism, or SNP.

However, according to Nevo, "Genetic Diversity" (Encyclopedia of Biodiversity, 2001),

Significantly, SSRs experience mutation at notably higher rates than do nonrepetitive sequences: $10^{-2}$ to $10^{-3}$ per locus, per gamete, per generation, which leads to their high polymorphism.

Additionally, according to Kashi and King, "Simple Sequence Repeats as Advantageous Mutators in Evolution", (TRENDS in Genetics 22(5):257),

Mutations that alter repeat number typically occur at rates orders of magnitude greater than single-nucleotide point mutations.

So, if variations in organisms is mostly due to SSRs, and this is mostly copy number variation, then would it be correct to say that copy number variants in SSRs is the dominant form of variation, or am I missing something?  Which one is correct, or which source is more authoritative, or is there a more up-to-date review I should be consulting?


texts: What is(are) the mechanism(s) that stop cells from fusing in vivo?

texts:
I just learned about the phenomenon of 'cell fusion' in which two diploid somatic cells can combine into some aneuploid cell in vitro and proceed to proliferate in culture. Apparently this can even happen interspecifically. My question is, what stops cells that grow naturally in the body from fusing all the time and creating abnormal cells?

Or, does this happen somewhat often and produce potentially cancerous cells, which are then destroyed by the body's normal regulatory mechanisms (I guess it could slip these as well and turn into a problem).

Could this be why we normally have many benign growths over the course of an animal's lifetime?

Any related reading would be super appreciated, thanks!


texts:
“Red neurons” are evident by about 12 to 24 hours after an irreversible hypoxic/ ischemic insult. The morphologic features consist of shrinkage of the cell body, pyknosis of the nucleus, disappearance of the nucleolus, and loss of Nissl substance, with intense eosinophilia of the cytoplasm.  -Robbins textbook of pathology

Taken from Robbins pathologic basis of disease, 9e, pg.no1265, fig: 28-13B

Why in case of neurons there is shrinkage instead of swelling as in other cells?


texts:
I'm trying to understand enzyme kinetics, the formula for Km and Kcat make sense to me.

  Km , the substrate concentration at which the reaction rate is half of Vmax

  Kcat, used to describe the limiting rate of any enzyme-catalyzed reaction at saturation. Most of the time
  Kcat just equals K2 (NOT the case when there are
  more reaction steps)

I can find information about the calculation of the specificity constant (Kcat / Km) and what it means:

  specificity constant,the rate constant for the conversion of E + S to E + P

However I can't find any detailed explanation WHY you should devide the Kcat by Km. Secondly Km is HALF of Vmax (so actullay at half saturation) but Kcat is at full saturation, deviding these two numbers makes no sense to me. So to summerize I'm asking : What is the "meaning" of the division of these two consants?

definitions are derived/edited from Lehninger principles of biochemistry


texts:
Turns out that you can do indoor farming these days via hydroponics and specialised LED lights. My mother, who has a large garden, warns me from exploring this as a hobby. She mentions that 'plants need to sleep too' and that having a LED light on them 100% of the time might be bad for them.

Is there any sense in this? Is it true that plants would grow suboptimally if the sun was on them 100% of the time or would they in fact grow quicker? Is there any research on this?


texts:
I am looking for the articles in which Lotka and Volterra published their original predator prey model. I couldn’t find the model presented in many textbooks in Lotka’s book Elements of Physical Biology or Volterra’s paper Fluctuations in the Abundance of a Species considered Mathematically.

Is there really Lotka–Volterra model for dynamics of two  competing species? On Wikipedia and Murray’s book Mathematical Biology: an Introduction, it is written that it exists but I couldn’t find it in their papers.


texts: How is the volume of the dialysis buffer decided?

texts: Is there a specific ratio between the volume of enzyme solution in semipermeable membrane bag and the volume of the buffer outside the membrane bag? I have been looking for a specific formula or general rules to decide on the volume of the buffer outside the membrane bag but to no avail. There must be general rules to determine the volume. It can't be come up with out of thin air. What common criteria are there to determine the volume as well as the time for the dialysis?


texts:
I am interested in using forskolin in cell culture medium. Does anyone know how to make solution of 10 microM forskolin in 5% ethanol or less. I would like to avoid using DMSO as a solvent.
Thank you. L.


texts: Is it common for an undergraduate to run their thesis (evolutionary genomics) in a supercomputer? In my country, few supercomputers exist, but I'm not sure how it is for bachelors in the US or Europe. I am writing my application to graduate school abroad and I want to know if it is a remarkable point I can use as hook to begin my statement.


texts: Does minimizing hunger maximize weight gain?

texts:
Due to the "obesity epidemic," there is a lot of focus on the causes of weight gain. We typically talk about strategies to cause weight loss, but what about strategies to minimize/maximize hunger?

Is there a way that hunger can be cured by eating a certain distribution of calories as a function of time? For example, if I have 2000 calories of food and I can eat it at any time, how should I spread out eating it over a day to maximize/minimize weight gain?  What would be the physical differences for me if I ate a small snack every minute of the day versus eating all 2000 calories at once?

Likewise what about weight gain? Would it be easier to gain weight if someone waits until they are very hungry and overeats during that hunger window, or if they eat over a wider window?


texts: Identify this organism I found in my food

texts:
I found this thing floating in my orange juice this morning.
I pulled it out and it appears to be some sort of protozoa or something. It's about a quarter the size of my pinky nail. Was not moving at all.

Should I be worried about this? Either way I will be notifying the store. Location is Okinawa, Japan.


texts: Could a trans-female person ever become pregnant?

texts:
I was told that a transgender person, which I will define as anyone assigned male or female at birth that identifies opposite to that assignment, could never become pregnant conceptually, due to the lack of hormonal pathways present in cis-male / trans-female person.

Are there modern medical methods that would allow for someone born male and is now trans-female to ever become pregnant or is it the case that medical science is not, nor ever will be capable of allowing for this?

Edit: I would say this is a different question than the suggested duplicate because someone who has AIS or CAIS would have a different anatomy than men assigned at birth, although not by much.


texts: Technique to test antibiotic resistance in a bacteria in presence of another compound

texts: so I have to 'quantitatively' assess a bacterial strain for its antibiotic resistance property (it is a specific antibiotic) in the presence and absence of another compound alongside antibiotic. What technique or protocol can be followed?


texts: Bioinformatics : Drawbacks of using ORA(Overlap Analysis)

texts:
What do you think are the potential drawbacks/weakness of using ORA to explain distinction between two phenotypes.

I identified a few which were the dependencies of DE and the statistical method used to filter the starting DE list.

Any other weakness?

Thanks


texts: Interpretation of picture of human chromosomes

texts: Does this picture show sister chromatids or homologous chromosomes? If they are homologous then what is YY? If they are sister chromatids then do homologous chromosomes ever appear like this (with the centromere)? Do sister chromatids exist only in prophase-I to anaphase-I of meiosis?


texts:
I could find a way which could find it by body oxygen consumption and there is another way to measure it by injecting drugs — measuring cardiac output by the so-called “indicator dilution method,” a small amount of indicator, such as a dye, is injected into a large systemic vein or, preferably,into the right atrium.
I read about it but didn't understand it very well.

Can you explain it and Which one is mostly used in clinics to measure cardiac output?


texts:
I'm haven't studied biology so excuse me if I'm getting something wrong.
I'm trying to understand how the DNA from a sperm and egg cause the egg too multiply and form a perticular shape (shape of a fetus). Or in case of plants how does dna in a seed cause the sapling to grow into a plant of perticular shape and size?
I mean how does DNA cause the cell to multiply and grow into hands and legs and heads of a certain shape and size in animals. Or to stems, branches and leaves in plants? How does DNA shape a living organism?


texts: Do blood vessels expand during angiogenesis?

texts:
I know that there are two usual ways of creating new blood vessels:

A new vessel sprouts from the wall of an old one,
A wall of cells grows down the middle of a vessel, splitting it into two.

I also know that capillaries are all the same size (about wide enough for a single red blood cell to get through). I also know that in between the major blood vessels and the capillaries, you have a hierarchical branching of differently sized tubes.

So my question is to do with, like. So if a new blood vessel starts to sprout, does it start off as wide at the base, as it's always going to be? (E.g. does it already know how many times it'll have to branch before getting to the capillaries, and choose its width accordingly?) Or does it start off smaller, but widen at the base as its ends keep branching?


texts: What is the meaning of "within-season variation"?

texts: I am reading a paper about phenology and climate change for my assignment and I found this concept "within-season variation", can someone explain it to me? and how it is related to changes over time?


texts: In oscillometric blood pressure measurement, why do we assume that highest oscillations correspond with mean arterial pressure?

texts:
As far as I've seen, the point on the oscillometric curve where there are greatest oscillations represents the mean arterial pressure (MAP).
My question is - why? What is the logic behind this assumption? Or is it just an empirically observed coincidence?


texts: Consensus sequence for selection of initiation codon in eukaryotes

texts:
In bacteria the AUG (or other) codon at which translation of mRNA is initiated is preceded at a precise distance by a sequence known as the Shine and Dalgarno sequence, to which the 30S subunit initiation complex binds through base pairing of the 16S rRNA.

In eukaryotes, in contrast, the 40S initiation complex normally binds to the 5′-cap of the mRNA and scans until it reaches the appropriate AUG codon — usually the first. Marilyn Kozak, who originally proposed this model in 1978, updated it later to try to account for the approximately 10% of eukaryotic initiations that do not occur at the first AUG. She identified a consensus sequence surrounding initiating AUGs and suggested that this was important in their selection. (see Wikipedia article entitled Kozak Consensus Sequence).

What is the current status of this consensus sequence now that so much more sequence and transcript data are available? Is there any evidence as to how it might function, e.g. by interaction with 18S rRNA in a similar manner to the Shine and Dalgarno sequence?


texts: If I receive dopamine only from doing difficult things will I eventually enjoy them?

texts:
I've recently read a post from reddit about how dopamine affects our motivation. Author states:

Dopamine is pleasure. Your brain craves more pleasure. You get too
much pleasure and your brain adapts to feel like tons of pleasure is
less pleasure then everything else becomes more boring. Cut those big
pleasure spikes out and everything else becomes more pleasurable. Your
dopamine receptors change to interact with less dopamine when you have
too much and when you cut down on dopamine, your dopamine receptors
change to interact with more dopamine. This makes boring stuff fun. Do
boring things long enough and endure until it becomes pleasurable via
dopamine receptors. And remember, think in terms of dopamine the next
time you feel like not doing what you need to do!

He advises to stop listening music, playing video games, watching porn, digital entertainment intake. He says:

This will make your dopamine receptors less dull over time and more receptive to lower levels of dopamine so doing things that are boring now will eventually feel not-boring if you can cut out big dopamine spikes.
Then, you keep doing the things you know you need to do but don't feel like doing long enough until your dopamine receptors become used to less dopamine and those things will feel good to do.

Some people accused author because of bro-science in his post. Can someone prove the theory or debunk it?
Will I enjoy doing difficult things which don't give me pleasure now if it's my only dopamine source?


texts: If species are reproductively isolated, then how are interspecific hybridisations carried out?

texts: during fertilisation there is compatibility test done so that both sperms and eggs are of same species. the zona pellucida of egg bears sperm specific receptor proteins(ZP3 receptor proteins) which bind with species specific proteins (bindin) present on sperm. so during interspecific hybridisaton( for example mule which is hybrid of donkey and horse) how fertilisation between gametes of different species carried out? what is exactly the mechanism behind this?


texts: How long can the brain survive during ongoing cardiac arrest?

texts:
There was this interesting discussion on CPR and defib in response to the question "Why can't we defibrillate the heart within 1 minute after ventricular fibrillation by electroshock?".

Now I was wondering "How long can the brain cope without O2?".

And to specify this question to a realistic situation: "How long can the brain survive a cardiac arrest without (gross) neurological symptomatic consequences?"

I would define "gross symptomatic consequences" as "noticeable and debilitating" in one way or another to the subject. This opposed to minute changes in, e.g., motor response latencies measured in a laboratory task designed to pick up the slightest results of asphyxia.

As background: I did these CPR and defib courses and the first thing they tell you to do is (1) call 911 / 000 whatever alarm number and (2) arrange a partner in crime to help with CPR;  or in case of a defib situation, (call alarm nr), make your way to the defib, unpack, apply electrodes, look at the manual, casually wait for instructions/warning lights etc. But..but... there is a person here without oxygen supply to his brain! And I know professional staff should be brought to the scene, but what struck me most is that starting up the defib (which inherently takes time) is more important than CPR (which is immediate)? In other words, loosing precious minutes is advantageous over diving straight away into CPR and pumping blood around?


texts:
How do you monitor the use of nootropics?

What is a good process to measure both: side-effects and any improvements.
Where can I find resources with scientific and tested data of short and long term usage of various Nootropics? (I'm using google as well)

Thank you!


texts: How Much Longer For The Gene For Blue Eyes?

texts:
In the year 1900 roughly 50% of the people in the United States were homozygous for the gene for blue eyes. By 1950 the number had dropped down to 30%. Just now, (2013) barely 12% of the people living in America are homozygous for the blue eye gene.

Given the current rates of third world immigration into the United States. When will the last blue eyed man and the last blue eyed woman conceive a child with blue eyes? Should people with blue eyes bring reverse discrimination suits?

Reference:http://www.boston.com/news/globe/living/articles/2006/10/17/dont_it_make_my_blue_eyes_brown/ By Douglas Belkin


texts: On vs. off-plant ripening: which one yields a more nutritious fruit?

texts: Many fruits may ripen either when attached to the plant, or once it is detached from the plant. Which option yields a more nutritious fruit? In other words, if one picks a fruit when it is still unripe, then wait for it to get ripe, will the fruit has similar nutritional properties as if one wait for the fruit to ripe before picking it?


texts: Do RNA modification proteins bind to specific repeats on the RNA polymerase II CTD?

texts:
The C-terminal domain (CTD) of human RNA polymerase II has 52 repeats of a similar heptapeptide sequence.
Will the RNA modification proteins only bind to some repeats at specific locations on this (e.g. the 1st repeat/the 10th repeat/the last repeat, etc), or will they bind randomly to any of the repeats?
If they bind to specific repeats, how can this specificity achieved?
If they bind to any of the repeats, then it would seem to me that several molecules of an RNA modification protein could be bound to a single RNA polymerase II CTD. Does this happen?


texts: Which of the three is true for insulin receptors?

texts:
I have seen the following question in a Cell Biology exam:
Which of the following is true"

Insulin has an hydrophobic Signal Peptide and the insulin receptor does not have an hydrophobic Signal Peptide

The insulin is coded by two genes, the insulin receptor has an hydrophobic sequence in the middle of the protein.

Receptors in the ER bound the SRP that is bounded to the insulin receptor, SRP is made of RNA and proteins.

I think that (1) is the right answer. However, people I talked with thought (3) is the right one.
I think 1 is right because I have never seen anywhere that insulin receptor has a signal peptide so I assumed it does not have.
I also think that SRP is a part of the insulin receptor, which is located on the ER (and not bounded to the ER by receptors), this is why I thought (3) is not the right answer.
Am I right, or did I miss anything?


texts: Physiology of skin and leather: why do salt borders occur?

texts:
I discussed a leather store about the white border aka salt border on leather shoes. They said that it is due to inner features of leather and you could try to add some fat/cream to push it back inside the shoes. I haven't yet understood physiology of skin here, "why does it act like that?" is the first doubt and then the second "does human skin act the same way?" -- I can see this kind of salt borders in gym clothes when they cry uncleaned but haven't seen them yet on my skin at least. The extra salty water from legs causes real damage, such as getting the inner fluids out, to the leather. When you do heavy training, the salty sweat in the human skin acts apparently the same way. So:

  how to manage the skin in living human skin and how does it differ from leather maintenance? What is the common physiological background with the different kinds of skins?

I try to answer it myself:

leather: you can add the fat/cream/etc only externally
living human ski: you can add the fat/cream-etc both internally (fatty food) and externally (lotions)


texts:
I tried to find the academic definition of deep exhalation/inhalation but found nothing special.

I speculate that the correct definition is as follows:

  • Deep Exhalation: Exhaling the air with effort as much as possible,
  after a normal "inhalation".

  • Deep Inhalation: Inhaling the air with effort as much as possible,
  after a normal "exhalation".

The corresponding volumes of the air which is being moved inside respiratory tracts would be:

Vdeep exhalation = Tidal Volume + Expiratory reserve volume (ERV)

Vdeep inhalation = Tidal Volume + Inspiratory reserve volume (IRV)

But, in case we define them as below, the previous conclusion regarding the volumes turns wrong and consequently should be revised.

  • Deep Exhalation: Exhaling the air with effort as much as possible,
  after a normal "exhalation".

  • Deep Inhalation: Inhaling the air with effort as much as possible,
  after a normal "inhalation".

Vdeep exhalation = Expiratory reserve volume (ERV)

Vdeep inhalation = Inspiratory reserve volume (IRV)

I think it's impossible to assess without any subtle definition. I'm really confused.

Any help would be highly appreciated.


texts: Why is a heritability coefficient not an index of how "genetic" something is?

texts:
On his blog, Eric Turkheimer writes:

  [T]aken as a number, a unit of analysis, heritability coefficients are
  funny things to aggregate on such a massive level.  What exactly are
  we supposed to make of the fact that twins studies in the
  ophthalmology domain produced the highest heritabilities?  Should eye
  doctors, as opposed to say dermatologists, be rushing to the genetics
  lab because their trait turns out to be more heritable?  No.  Whatever
  else a heritability may be, it is not an index of how "genetic"
  something is.  It is not, for example, a useful indicator of how
  successful gene-finding efforts are likely to be.  If nothing else,
  differences in reliability of measurement are confounded every
  heritability tallied here.  My point is this-- although it's nice to
  know that on average everything is 50% heritable, it's hard to attach
  much meaning to the number itself, or especially to deviations from
  that number, to the fact that eye conditions have heritabilities
  around .7 and attitudes around .3.  Having two arms has a heritability
  of 0.

As I understand this, one reason Turkheimer believes heritability coefficients are not an index of how genetic a trait is is that they are confounded by varying levels of measurement error. So, for example, maybe the relatively low heritabilities in skin conditions compared to eye conditions are because there is more measurement error in relation to skin conditions.

Turkheimer implies that there are other reasons why it's not appropriate to say a heritability coefficient is an index of "how genetic" something is. What are those other reasons?


texts: Convergence compared to genetic distance

texts:
Is there an information (preferably in the form of a chart, though anything will do) comparing convergent evolution to how closely related the 2 species are on the tree of life.
My searches for anything touching on this subject have returned nothing

Context:
I was having a discussion with a friend on how similar we should expect alien life to be to earth. The topic of high levels of convergence on earth being indicative of convergence between life on Earth and life with a seperate origin on another planet came up. However it appears to me that convergence tends to happen a lot more in more closely related species, but I have no solid data for or against this idea. For example I don't think any plantae have developed any significant ability to move, like animalia have, which I find surprising as it is a very broad ability.

Please note my knowledge of biology is only on a general level.


texts: On which part of the DNA will the new DNA nucleotide connect?

texts:
My question is:

  Where will the new DNA nucleotide connect on the (part of the) DNA shown on the picture? Will it connect to the phosphate group?

What does the 5' --> 3' mean?

Thank you in advance.


texts:
Amongst silent, nonsense and missense genetic mutations, is the latter the only one that leads to the creation of new alleles?

If we define alleles as a specific form of a gene, and a gene as a heritable factor consisting of a length of DNA that influences a certain characteristic, since the missense mutation is the only one that leads to the physical creation of a new protein, is it not the only one that would lead to the creation of new alleles?

Or would nonsense also lead to new alleles as the lack of the protein may lead to the expression of a different characteristic?


texts: Does human skeletal muscle fascia grow new additional collagen in response to increases in skeletal muscle size?

texts: For example, if a human skeletal muscle is growing repeatedly due to periodic weightlifting, does the fascia eventually respond to the increasing volume by growing more quantities of collagen or other components to accommodate the growth? Or rather, does it only expand by "stretching" the existing amount of collagen without the growth of new material to accommodate the changes in muscle size (except perhaps to repair possible wear/damage that might've occurred during exercise)?


texts: This is a stink bug that I found in Indiranagar, Bangalore. It was dead at that time and had become stiff, so the following are the best pictures I could get. It is 2cms in length. I tried searching on the net on various websites but I didn't find a match for the colouration on the dorsal side. Also, I would like to know what those protrusions on the top half of the shield ( excuse me if 'shield' is the wrong terminology) are. They seemed to be quite a troublesome feature as none of the reference pictures I saw on the net seemed to have bugs with these 'protrusions' .


texts:
Good pipetting technique is essential for many biologists, but it can be hard to get right. When I take 1 µl of liquid using a micropipette, I seem to always take less than 1 µl, and that amount is variable/inconsistent. I would like to know what could be wrong.

What is the proper pipetting technique? Could it be that the pipette is inaccurate?


texts: What is an "open system" when it comes to PCR machines?

texts:
I have heard the term "open systems", such as here when it comes to RT-PCR machines, but I'm not 100% sure what this means, does this mean machines you can purchase yourself? Such as this one? ... compared to one that would be in a lab?
Also, I have heard that they come with the statement that they are for research purposes only and should not be used as a diagnostic tool, is this because anyone can buy them?


texts: Do there exist publicly available Genome sequences of a family?

texts: I would like to explore the genome sequence of a publicly available genome sequences of a family (like mother, father, son, daughter...). If such human genome sequences are not publicly available at least any animal's family data is also OK. :)  I am not a biologist, but aims to just understand things more clearly.


texts: I should be grateful if anyone would send me a link to an article or an encyclopedia/handbook contaning an explanation of the concept of enzymatic activity. Surprisingly, I did not manage to find anything else but a brief definition.


texts: What is the exact frequency of Delta brain waves during Slow Wave NREM Sleep?

texts:
I saw a TED talk about researchers playing pulsating pink noise while a test subject is in Stage 3 Non-REM / Slow Wave / Deep sleep and observing an increase in Delta wave EEG activity. This seems to indicating that the burst frequency of the pink noise is matching the dominant frequency of the Delta waves. (Skip to 5:00 to hear a sample of the sound)

My question: While a spectral analysis shows a range of brain wave frequencies, and many sources define a range such as "0.5-4 Hz", I'd like to find a more precise dominant frequency of Delta waves.

The video inspired me to write my own small computer program to make my laptop play a similar pulsating pink noise pattern on the table next to my bed last night. I arbitrarily chose 1 Hz as the pulse frequency, and the following pattern:

30 min silent (to give me time to wind down and fall asleep)
  60 min sound
33 min silent
  54 min sound
40 min silent
  45 min sound
49 min silent
  37 min sound
57 min silent
  30 min sound
30 min silent

So roughly 5x 90-minute sleep cycles with an increasing ratio of silence to noise to mimic the ratio of REM to NREM as the night progresses. I've read that REM is characterized by un-synchronized brain waves and NREM is where you see large amplitude synchronized Delta waves which the sound experiment is trying to help stimulate. Tonight I will wear my FitBit bracelet with heart rate and sleep stage tracking to see if the readings match the sound schedule.

Bonus Questions:

How credible is the hypothesis that playing sounds can affect the quality of sleep?
Would a different sound than pulsating pink noise work better?
Does the phase matter?
Also, I couldn't help but notice that Deep NREM sleep seems to be the only time you see a single large amplitude frequency dominate on EEG and it's suspiciously close to the average Resting Heart Rate of 60 bpm...are Delta waves and heart rate related?


texts: Are all action potentials the same shape and amplitude when graphed with respect to time?

texts:
The most common visualization of an action potential is a graph of the difference in membrane potential (y axis) at a particular time (x axis).

According to my textbook Cognitive Psychology by E. Bruce Goldstein, an action potential sent from neuron down the axon remains the same. That is, if we plot the action potential as described above, then at each as it is propagated down it will have the same shape on the graph (within some range of error obviously, but he is saying the error is trivial).
But he then says on page 34

  One way to answer the question of how action potentials determine different qualities [(e.g. taste of something sweet)] is to propose that the action potentials for each quality might look different. However, [Edgar] Adrian rules out that possibility by determining that all action potentials have basically the same height and shape.

My Question

Can someone confirm these two facts:

Once an action potential is sent from a given neuron down the axon, does the shape and amplitude remain constant as it is propagated?
Do all action potentials have the same amplitude and shape?


texts: Are myosatellite cells myoblasts or do they differentiate into myoblasts?

texts: Can satellite cells immediately fuse to a myotube/myofiber (meaning it is a myoblast already) or do they differentiate into a myoblast first and then fuse to myotubes/myofibers?


texts: How necessary is human zygote cytoplasm for generating a human?

texts:
I'm primarily questioning the roles of genetics and cytoplasmic factors of zygote in generating a human being with a natural embryological process.

For instance, is there an experiment where we check if we get a human when we replace the DNA of a mice zygote with human DNA?


texts: What is the difference between Reservoir and paratenic hosts?

texts:
Paratenic host

'In parasitology, the term paratenic describes a host that is not necessary for the development of a particular species of parasite, but nonetheless may happen to serve to maintain the life cycle of that parasite' until they are transferred to an obligatory host.

(from Wikipedia and Parasitology: A Conceptual Approach book)

Reservoir host

  Reservoir hosts are such animals which accumulate in themselves the invasive larvae of the helminthes and contribute to their transfer to the definitive host, not being however an obligatory condition for the complition of parasite ontogenesis.

(from Proceedings of the First International Congress of Parasitology: Roma, 21-26 September 1964)

The source however says that Reservoir host is same as paratenic host which contradicts other sources
(like General Parasitology by Cheng) which says:

  Reservoir host is an animal that becomes infected and serve as a source from which other animals can be infected. (the only difference I presume is that it may or may not be obligatory)

In many other books (book 1 & 2) a parallel definition is mentioned that a reservoir host is a host that harbors parasite until their transmission to human beings.

This inturn brings forth another question, is a reservoir host a biological vector then?

So the question : Are paratenic host and reservoir host same or different?

P.S. I don't know what the standard books on parasitology are which could have solved this issue. Reference to one such book will be really appreciated.


texts: Aren't current explanations for the evolution of human cooperation a little too reductionist?

texts:
Lately, I've become a believer in the limits of reductionist explanations especially in areas like complex systems and biology. So, without wasting any more time, I'll get to my question..

Whenever we think of something like cooperation, the most common explanation that comes up is that of genetic fitness. It is said that evolution would have selected for psychological mechanisms of cooperation because it is beneficial in a society in which reciprocity is possible. You scratch my back, and I scratch yours. Add to the mix the ability to name names, and reputation becomes a kind of proxy signal for fitness.

Now, the major problem I have with this is does it all have to boil down to fitness? Can't it be a phenomenon that is culture-specific? Different cultures go to different lengths to help a stranger. Yet, we all share the same evolutionary history. This seems like a strong indicator that cooperation can't be reduced to one's genetic or reputational fitness alone. Should the study of cooperation be handed off to the anthropologists?


texts: Why are human mothers told to "push" out a baby?

texts:
I've always wondered why human mothers are instructed to "push" when giving birth.

Every other animal just gives birth of it's own accord. Albeit perhaps from a different position with the help of gravity. You don't have to tell a giraffe to push.

But for some reason humans feel like mothers can only give birth through conscious will power.

Surely, if the mother just let the body do it's natural thing, the baby would come out just the same.

What's more, I would expect that if the mother was consciously "pushing" using the wrong muscles this would hinder rather than help the birth. (Does a woman even have mental control over this?)

Also, what's the rush? As long as the umblical cord is still attached, should it matter how long the birth takes?

When did this idea of telling the mother to "push" first start, and is it common practice around the world?

Here is an article which questions this idea: https://curiosity.com/topics/should-we-stop-telling-women-to-push-during-labor-curiosity/


texts: Are differing shapes of the acromion congenital or acquired?

texts:
In the human body, the acromion is located here:

There exist different shapes of acromion, at least 3:

The frequency varies according to the acromion type:

Some clinicians consider that there exist more than 3 types of acromion:

Are differing shapes of the acromion are congenital or acquired?

{1} says:

  Debate continues as to whether the differing shapes of the acromion are congenital or acquired. […] We conclude that the different shapes of acromion are, therefore, acquired as a response to traction forces applied via the coracoacromial ligament and are not congenital in origin.

However, this study was published 16 years ago. What is the current scientific consensus, if any, regarding whether differing shapes of the acromion are congenital or acquired?

References:

{1} Shah, Nirav N., N. C. Bayliss, and Archie Malcolm. "Shape of the acromion: congenital or acquired—a macroscopic, radiographic, and microscopic study of acromion." Journal of Shoulder and Elbow Surgery 10, no. 4 (2001): 309-316. https://scholar.google.com/scholar?cluster=2046701264133216154&hl=en&as_sdt=0,22 ; http://doi.org/10.1067/mse.2001.114681; http://sci-hub.cc/10.1067/mse.2001.114681


texts: Is aneuploidy/aneusomy only a problem for cell division?

texts:
One of my textbooks states that:

  "recent studies suggest that aneuploidy can be seen in upwards of 10% of human brain cells without any noticeable effects"

I do know that trisomy 21 causes problems, specifically mental retardation by not allowing the brain to turn certain genes ON and OFF at certain protein levels, but I do not understand why plants are okay with aneuploidy?

Is it because plant cells are more "plastic" than animal cells that, they are okay with aneuploidy?

Because neurons never divide, do they never have to deal with aneuploidy?

Or is aneuploidy a problem of stress that results from failing to control gene expression?

or is it a problem strictly of mitosis?


texts: Name for a set/collection of eggs which are laid and receive no nurturing of any sort by parents

texts:
OK - so, mammals have litters, and they look after their young.

Hens (birds generally) have clutches and many/most look after their young.

Octopuses have broods since the female looks after the eggs, but expires
just as they hatch!

The thing I want to know is:

What is a group of eggs laid by a creature which just lays them and
moves on called?

Also of interest would be such creatures which lay single eggs periodically (is there a difference?).

I'm particularly interested in insects and the like, but any additional
words which may apply would be of interest, and yes, I have Googled but
to no avail!


texts: Why aren't circadian rhythms exactly 24 hours long?

texts: Most organisms exhibit circadian rhythms that have a periodicity of about, but not exactly 24 hours. Why is this? And to what extent can variation in periodicity in circadian rhythms among the individuals of the same species (if a variation does indeed exist) influence the level of competition they face in acquiring resources?


texts: What fraction of human cells gets infected during a viral infection?

texts:
As I understand, if a cell gets infected during a viral infection then it eventually dies. If an individual does not die of an infection, the percentage of cells that gets infected in the course of the infection must be quite low.

Are there any estimates available on how many cells get infected during a viral infection? (say, an influenza infection)?

(A very similar question was asked five years ago but unfortunately received no answers.)


texts: Imagine I am preparing food -- just about to put it into a microwave oven --  and some of it falls on the floor. Assuming it got some bacteria or other organisms (viruses?) on it, will the microwave processing disinfect it? What about worm eggs? As I understand, any living organism, given enough exposure to microwaves, degenerates. Is this true?


texts:
It is said that beehives once queenless try to rear a new one by themselves. Beekeeping resources, books, websites, youtube videos, etc. have a very pragmatic human-centered view to the issue: what should the beekeeper do and don't. Some say, that the beehive can potentially rear a new queen on their own. I've also heard from beekeepers that they can be helped by introducing an extra brood comb from another hive.
I am interested in knowing the details on how this re-queening process takes place without human intervention.
Queens, like workers are female, hence they must come from diploid eggs. Hence only a mated queen can provide the egg needed to produce a new queen. Also it is known that queens are reared inside special queen cells which lie in vertical position in the comb.
It is known and it can be easily observed, that if the queen dies unexpectedly, the hive prepares for a substitute by building queen cups (will be queen cells).
But I wonder how do they actually get a queen from those cells.
The workers must either

carry an egg, previously laid by the former queen, from a worker cell into the cup,
or build the queen cup around a cell that already has an egg, or a young larva.

I can't imagine any other possible way.
So, how does exactly the requeening processes takes place?
Update. To be more specific about the details of the process of requeening I would like also to add the following questions:

Do they start breeding a queen from an egg or a young larva?
Do they choose this egg/larva at random?
Do we know a probability distribution for queen hatching dates? ie. the probability of a queen emerging (starting from a 0-day egg) after 15 days, 16 days, 17 days, etc.
What's the attitude of worker bees with respect to queen cells? Can a queen cell be destroyed by worker bees under certain circumstances?


texts: What is range of the number of individual organelles in cells

texts:
What is the range of the number of individual organelles in a cell?

I am not a biologist but I understand that there's one nucleus and sometimes lots of mitochondria, so I am after the total number.

I understand that different types of cell will have a different number of Organelles in them, (e.g. there might be some very simple cells with 10 but there might be some with many more than that) but I am after the range with some examples. (I need references)

This is for a computational model.

Thanks very much


texts:
The following commentator writes:

  Researchers at UCLA and the University of Wisconsin–Madison have confirmed that microscopic fossils discovered in a nearly 3.5 billion-year-old piece of rock in Western Australia are the oldest fossils ever found and indeed the earliest direct evidence of life on Earth.

It seems strange that this would come up recently. I thought there might be something older.

My question is: Are these 3.5B year old fossils the oldest on earth?


texts: Why is thymine not incorporated into mRNA?

texts: I am aware that in transcription uracil bonds to adenine and not thymine. But what is it that actually prevents thymine from bonding to adenine in transcription, that is not present in replication?


texts: How a particular composition of molecules result into life in form of cell?

texts: I had read biology in childhood only, but as far as I can remember every living thing/being is made up of cells in the lowest level. Cells again are made up of some particular composition of molecules. But my question is how a particular composition of molecules become alive? Or What's that which turn compositions of molecules sentient?  I'm trying to understand when or how insentient compositions of molecules become sentient.


texts: Scoring sequence against position weight matrix

texts:
I have a weight matrix of length 20 x 15 (amino acids x sequence positions). Each element of my weight matrix is a relative probability

If I have a sequence say "AAPGTGASMHSGLLW" how would I score it against the matrix? I tried taking the product of probabilities corresponding to the matrix, but I end up with a really small number

Any ideas?

Edit:

Consider the simple matrix:

    1    2   3     4
A 0.3 0.90 0.5 0.0001
B 0.2 0.05 0.4 0.2
C 0.5 0.05 0.1 0.8

The best match is, with a score of:

CAAC = 0.5 * 0.9 * 0.5 * 0.8 = 0.18

If you change the first letter to an B instead of C

you get a match, with a score of:

BAAC = 0.2 * 0.9 * 0.5 * 0.8 = 0.072

Which is a huge difference for such a small change...
This is even worse with my larger matrix since the score is easily affected by small probabilities


texts: What is a coupled reaction and why do cells couple reactions?

texts: I was wondering what exactly a coupled reaction is and why cells couple them.  I read the wikipedia article as well as several others, such as life.illinois.edu but I still don't get it.  Could someone explain it to me?


texts: What are the costs associated with carrying lots of genetic material

texts:
What are the costs (if any) associated with carrying lots of genetic material (Big genome size)?

energy for copying?
raw material for copying?
space in the cell?
Maintenance cost (matter and energy)?
time to copy is a limiting factor for the minimum generation time?
Less robustness?
More likely to evolve a gene that spreads well but has a negative fitness impact on the rest of the genome (selfish gene or outlaw)?

The answer probably depends on the organism. I am interested about any information concerning uni- or multi-cellular eukaryotes, bacteria or viruses.

Do we have any knowledge about how important are these costs or is it pure guesses?

This post comes in reaction to @AlanBoyd comments on this post.


texts: Inward rectifying potassium channels during undershoot of action potential

texts: My professor said that inward rectifying channels help move the membrane potential back to the resting potential during the undershoot phase of the action potential. The membrane potential would have to be lower than the equilibrium potential of potassium for this to occur (inward potassium driving force), but the membrane potential never goes below the equilibrium potential of potassium during the action potential. So, when are potassium rectifying channels actively passing ions?


texts: Why is Mus Musculus a good model organism?

texts:
I'm reading through a number of articles that use partial hepatectomy in Mus Musculus to study the mechanisms for liver regeneration (1, 2, 3). I have no doubt that a better understanding of hepatocyte regeneration mechanisms will allow scientists to discover/create new theurapetic targets that would improve liver regeneration in mice. However, these articles seem to imply that the results of the research will be applicable to liver regeneration in humans as well.

What makes Mus Musculus a good model organism? I'm inclined to think that some mouse genes might have homological human genes; is there more to that? Bonus points for answers that would show how research on non-coding RNAs, as compared to protein-coding genes, in mice would apply to humans.


texts: Why is it that honey can last for decades and not spoil like other foods? Is there any chemical in honey which gives rise to this amazing feat?


texts: Does homology of a trait necessarily imply that the most recent common ancestor had the trait?

texts: If two different species have a trait that is homologous, does this mean that the most recent common ancestor necessarily had the same trait?


texts:
Many documents (e.g., this, this, and this) state kangaroo rats are special because they can use water produced by metabolism. Is the metabolism of kangaroo rats more efficient in producing water than that of other organisms?

Or the metabolism mechanism of kangaroo rats is the same as other organisms, but kangaroo rats can subsist with little water produced by metabolism because they conserve water from various mechanisms?


texts: Infer gene frequency within a species over time

texts:
I was reading Karlsson et al. (2014) and I came into this:

  A selected variant that increases rapidly in frequency in the past ~250,000 years can be detected as an unusual reduction in genetic diversity.

I realised that I do not know how to infer a specific allele frequency over time within a given species.

I tried to googled some keyword but was flooded by other concepts. Could you please direct me to some appropriate documentation/kewords?


texts: Protocol for checking pipette calibrations using absorbance readings of a dye in solution?

texts: I've been looking around the net looking for a nice protocol to validate micropipette calibrations using absorbance readings of a dye in solution. Does anyone have one they can share? I'd highly appreciate it!


texts: Before doing any GWAS (genome-wide association study) it is necessary to check for the normality of the phenotypic distribution. If the phenotype is normally distributed only once it is log-transformed, what phenotypic data do I have to use while doing the GWAS? The non-transformed one or the log-transformed?


texts: Can the Hebbian theory apply to Inhibitory Neurons

texts:
If I understand the basic Hebbian theory, when a neuron fires a pulse to another neuron and this pulse causes the target neuron to fire then the delta energy sent from the initial neuron to the target is increased. (Making it easier to trigger the target cell)

With this in mind is there a way for an inhibitory neuron to increase the delta energy it applies to a target neuron (reducing the excitation level of a target neuron).

If the inhibitory neuron never triggers the target then I would assume it would never increase the decrease in energy it sends to the target.


texts: Would it be possible to regulate proper phosphorylation so the UPR wouldn't initiate a reactionary cell death in important cells?

texts: In studying the correlation of folded versus unfolded proteins and their impact on neuro-degeneration, it looks like improper phosphorylation in the chaperones (at least, in part) causes the mis-folding of proteins? If so, would it be possible to regulate proper phosphorylation so the UPR wouldn't initiate a reactionary cell death in important cells?


texts: Does biofuel production by microalgae need an extra source of CO₂?

texts: It is necessary to have extra source of CO2 i.e. from a nuclear reactor or factory chimney to produce bio-fuel by microalgae or is it able to do it with the normal CO2 density in the atmosphere?


texts: What is full form of r and K in r-selection species and K-selection species?

texts: What is full form/ meaning of 'r' and 'K' in r-selection species and K-selection species? Does this 'r' means "Random" and the 'K' means "constant"?


texts: Why is it unlikely that bathroom smells can pose health risks?

texts:
Based on a little bit of internet reading, it appears that odor molecules that enter your nose from human feces are of little concern to your health because the harmful stuff, like the pathogens, are not likely to be picked up and carried through the air.

This seems to make sense, however due to my limited knowledge of biology, I am having a difficult time distinguishing WHY the bad stuff is not likely to become airborne whereas other molecules can, and will cause damage by smell. Chlorine, for instance, will cause some significant damage simply by smelling the airborne fumes (which I assume are the molecules doing the damage).

I have to assume it is a natural defense mechanism that something that smells bad is not something you want to be around (CO being a major exception) but it seems that feces molecules are not a concern. Why?


texts: What insect is this? Found this at home, India

texts: Found this insect in Kolkata India. Has a sting at its rear end. The wings are shiny.


texts: Question about flux and changes in net flux of molecules across a membrane

texts:
I've been reading a book called Principles of Human Physiology by Stanfield 5th edition, and was reading a chapter on membrane transport when I came across a figure question which will be posted below.

It says "As time passes, does the one-way flux from side 2 to side 1 increase, decrease, or stay the same?"

I have unfortunately been unable to comprehend why and how the answer is "Increase". I would suppose it stays the same, correct? There is no possible way that a flux would occur, unless by individual molecules (regularly) passing through each side on a equal basis.

It was a topic on Simple diffusion.

P.S. This book, as i've noticed hasnt been quite explaining some things in a clear-cut way to understand as a beginner, and also it has had some mistake within it.


texts: Is there any data on Neanderthal admixture in Western European Hunter Gatherers?

texts: If there is any data, was the rate of admixture higher than today? Like WEHG brought the component in? Or was the amount maybe lower, like other groups like Early European Farmers or Yamnaya brought the admixture? Or was it evenly distributed?


texts: Why exactly does a scarf help against a neck pain and a sore throat?

texts:
I was going out without a scarf and as this day my neck
was more sensitive; after a while my voice was
rasping, I needed to cough and my neck was hurting
slightly.

After coming home I put on my silk scarf and the effect
was almost immediate. The pain cedes and my voiced normalized.
Why exactly is the warmth provided by a scarf so quick and
effective for our neck ? I can see that isolating the neck
is more effective than a warm room (air is a bad heat conductor),
but why does the warmth help us to combat rasping and coughing ?
What causes rasping and coughing by the way ?


texts:
I am not an expert but I guess that mangroves (or some other plants that thrive in sea water) perform some kind of desalination to extract fresh water from sea water.

Is this true? If yes, What biological mechanisms are used to remove salt from sea water?

I am interested in any research about biological desalination.


texts: All flowering plants gives fruits. Why does jasmine flower plant not yield fruits?

texts: My question is actually my long term doubt. I have seen most of the flowers turning into fruits. But why not this jasmine flower?


texts: Do carboxylesterases, arylesterases and acylesterases count to the enzyme class of lipases?

texts: I am currently examining the acyl transfer catalysis activity of several enzymes that I was told are all lipases. Through reading a couple of papers including these enzymes I found out that all of them are hydrolases with promiscuous acyltransfer activity. Specifically one of the enzymes is a carboxyl-esterase, one is an aryl-esterase and the third one is an acyl-esterase. I know that esterases are part of hydrolases and lipases are basically fat-splitting esterases. Lipases also catalyze transesterification = acyl transfer, just like all of the enzymes I am working with do. I just don't understand the classification of all these enzymes as lipases. Can someone explain the connection to me?


texts: How to deduce if RNA virus infection or DNA virus infection

texts:
Is there any general rule to say this must be RNA virus infection and the other one DNA virus infection?

Example of a case: 5 children develop a bright red rash on the face and turns violet after a few days and then disappears. Then maculopapular rash appears on the trunk, buttocks and extremities. It soon fades from the trunk but persists on the thights and forearms. Two children have also had a slight fever and a sore throat, but all were not terribly sick. What is the genetic material of the most likely causative agent?

Right answer is: Single-stranded DNA, since most probably causative agent is erythema infectiosum caused by parvovirus B19.

I do not want to remember all microbes by heart.
How can you deduce that this must be a DNA infection and probably single-stranded?


texts: Which birds are capable of flying both forward and backwards?

texts:
Very random question - but it's often said that the hummingbird is the only bird that can fly backwards (for example, https://www.worldatlas.com/articles/which-is-the-only-bird-that-can-fly-backward.html).

Is this true? Aren't there any other birds that can fly both forward and backwards? Is it some kind of bird category of its own?


texts: How do transgenic transformations cause off-target phenotypes?

texts:
I read that transgene insertions can cause off-target mutations that result in a phenotype being overly ascribed to the transgene, e.g. the increase of lifespan being ascribed to Sir2 overexpression (Burnett et al, 2011, https://www.ncbi.nlm.nih.gov/pubmed/21938067). In that particular study, they outcrossed the transgenic strain several times with wild-type to remove these off-target effects, a mutation in Dyf2 being named in particular.

I have a poor background in genetics, so I don't really understand how transgene insertions can cause off-target mutations, nor how outcrossing can isolate the intended mutation.


texts: Visualizing GFP in transgenic rice seeds?

texts: I want to express GFP in rice as a method for differentiating transgenic from non transgenic rice seeds. I want to know if I can visualize them using a hand held UV lamp as the GFP I will be using has a excitation maxima at 395nm. If yes, how is to be done? Do I just flash the UV lamp on the seeds in the dark room and I can see the GFP expressing seeds glowing green?


texts:
There's a video I found on Facebook and I'm unable to figure out what the creature featured happens to be.
Adding images that have been taken from the video itself, apologies in advance since they're not high qualify images.

Can anybody shed any light on what it is?
The video was shot near Ratan Babu Ghat which is situated along the bank of Hooghly river, Kolkata, West Bengal, India. Here to be precise.


texts: Is it possible to artificially select for flight in pigs?

texts: After reading this rant by Fodor, as a layperson, I was idly wondering whether it would be possible to artifically select for flight in  pigs. Of course by that time the porcine lineage will probably comprise an entirely new species, but what would be the first step in our breeding experiment? And how would it develop thence, hypothetically speaking?


texts: Identification of this humpbacked, brown, clawed insect climbing up my wall?

texts:
I noticed several of these guys outside, all in a vertical position clinging to a wall. I didn't come to them too closely, but my immediate reaction was that they are scorpions.

I thought that maybe it's a curled-up scorpion, or maybe there's some kind of particular scorpion that is this circular in shape? These are probably silly conclusions, but I'm not an expert in this field. I would really appreciate the insight of a professional!

thanks very much.


texts:
In recemose inflorescence

Main axis continues to grow,
The flowers develop in acropetal succession ,
Opening of flower is centripetal

But according to definition

Acropetal succession : flowers opening in succession from base to apex
Centripetal : the younger flowers are towards the centre and the older towards the outside...

I can't understand that if lower flowers or flowers towards centre open first then they should be older but according to above statement flowers at base are younger. Is there other concept that I don't know?


texts: What is this type of diagram called and how to interpret?

texts:
I'm just starting a project on neuroscience for sixth form. I have had no teaching in this area so had to teach myself entirely.

This is a "low-power image of a transverse section through
the telencephalon of an adult pigeon":

I understand the TH means tyrosine hydroxylase but I have no idea what the different colours mean.

Any information would be so helpful :)

thanks very much!


texts: What is the actual biological difference between mice and rats? Are they actually the same thing with two different names depending on appearance (are they all mice for instance and we call the larger ones rats or vice versa) or is there some fundamental difference in their genetics?


texts: Can somebody be deaf to voices of some people only?

texts:
The voice of females is generally of high frequency, while that of males is generally of low frequency.

Also, as we age, we gradually keep losing the ability of hearing sounds of high frequencies.

So, can such a situation occur when a person is not able to hear voices of females, or maybe of certain people, while he can hear the voices of other people? I tried searching about it, but found nothing.


texts: When salivary amylase breaks down starch, are those substances tagged or destined for a particular use in the body

texts: When salivary amylase breaks down starch, are those substances identified for a particular use in the body?


texts: Is there a DNA test to identify dog mixes?

texts:
We adopted a dog at the age of two. Our vet said it was a mix of an Australian Shepherd and Border Collie, which we've told everyone. Based on markings, I think it's likely. I am wondering, however, if there are any tests or other ways to know the mix of a dog if you don't know the specific parentage.

Does each dog breed have specific genetic markers that can be used to identify the breed? If so, has a dog breed test been developed or is there no commercial demand for such a test?


texts: Who would win in a fight: an amoeba or a leukocyte?

texts:
(sorry, I couldn't resist the rhyming, silly title)

I find it facinating that humans can suffer from an amoeba infestation. Amoeba must reproduce far more slowly than bacteria. In size, they seem to be approximately the same size as the various leukocyte cell types (I see estimates ranging from 10μm to 30μm in diameter). I would assume that they are slow-moving, or, at least no more motile than a leukocyte.

How is it, then, that a population of amoeba can take up residence (and a particularly dangerous one, at that) in a human body without them being wiped out by the immune system? Do we know much about the pathology of such an infection? Do the amoeba actually consume the leukocytes by phagocytosis before they can be consumed themselves?


texts: Now I just learn that estrus is a trait in all mammals except Humans. So does it occur significantly in Humans? Of course I'm aware of the cliched "horny", "aroused" etc., but is it a biological function in Humans too? and if so, when and what is it called?


texts:
Question 1: Why does the immune system not act on sperm cells as sperm cells are developed after puberty?

Question 2: Does immune response occur when a person's own cells are injected inside their bodies?


texts: Is an X ml dose of a drug at 50% bioavailability roughly equivalent to a 2X ml dose at 25% bioavailability?

texts:
For the sake of simplicity, assume:

The two doses are the same drug metabolized in the exact same way, and the only difference is the amount that reaches the bloodstream (and thereafter the brain).
This drug is only meant to influence the brain, so differing concentrations in various organs don't matter.
This drug is short-term and nothing lingers in the body after it has been excreted or broken down.

My understanding is that bioavailability means the proportion of drug that reaches the bloodstream. So, all things being equal, does that mean an administration of a drug will be twice as potent if the bioavailability is doubled?


texts:
Background

There are many receptor types in the body, with various functions and various mechanisms of transduction. Receptor cells are considered to be part of the peripheral nervous system, as they are the first step in conveying information from the periphery to the brain.

Many receptor cells do not fire action potentials. Action potentials are widely considered to be a key property of neurons. Instead, receptors often operate by graded responses. For example, upon illumination photoreceptors gradually hyperpolarize. Cochlear hair cells gadually depolarize when the stereocilia are bent into one direction and hyperpolarize when they go in the opposite direction. Hence, many receptors are in fact analog sensors, whereas spiking neurons can be considered to be operating in binary (all-or-nothing) mode.

Given their similarities and differences, are receptor cells classified as neurons?

Credits: This question was formulated after a discussion with @OneFace on the question "Relationship between nerves and axons"


texts:
What is a suicide plasmid?

Example: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2737453/ mentions a "suicide vector". See also http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/plasmids/allele-exchange.html which also mentions them.


texts:
People are beginning to seriously research space travel applications of therapeutic hypothermia, specifically for reducing metabolism and stress on humans traveling to Mars.

It seems that as you decrease the temperature, the metabolism decreases. My question is regarding the relationship between ageing and metabolism. Do we have any data that answers the question if lowered metabolism also lowers the rate of ageing?

I'm wondering if these hypothetical astronauts going to Mars are actually losing 6 months of their lifespan in an unconscious state, or is their ageing rate being lowered as well? And by how much?

For the sake of simplicity, let's ignore the effects of radiation on ageing during the travel.


texts:
One day I had found some bees have come around the light source like other positively photo tropic insects, I hadn't seen any bees coming over light before. I think bees are diurnal and they don't leave their nest at nights, I also read from an article that parasitic wasps may attack bees and these attacked bees would lose their mind and leave their nest at nights.

Is this possible or any other reason behind the night travel of bees and their positive photo tropism ?
http://en.wikipedia.org/wiki/Apocephalus_borealis


texts:
We've been learning about fruits (and the various categories thereof) in class; among them we have the nut and the drupe.
My textbook differentiates between those terms as:

Nut: It is a single-seeded indehiscent, dry fruit.

Drupe: A fleshy fruit with a stony endocarp.

How here's the problem.
My textbook lists the walnut (fruit) as a nut. But Wikipedia disagrees on this point, calling it a drupe instead.

I'd like a second opinion, since both my book and Wikipedia have had reliability "issues" in the past.
Q- Is a walnut (fruit) a (botanical) nut or a drupe?


texts:
Let us consider a situation in which the body is attacked by a microbe, and  the microbe is captured by the immune system for recognition of surface antigens.
The surface antigen recognized mimics one of our self antigens.
It is stated in textbooks that this situation results in the immune system attacking  the microbe along with the tissue containing the self antigen(auto-immunity).
(Reference: Robbins and Cotran pathologic basis of disease)

If a microbial antigen mimicks self antigen, why is the microbial antigen attacked instead of being ignored in the way that all our self antigens are ignored by our immune system?


texts: Tree census data for Sweden/Scandinavia?

texts: Is anyone aware of any attempts to count or approximate the number of trees there are in Sweden or Scandinavia? I have a small popular science side project for which this would be useful


texts: How much of the Neanderthal genome is living on in humans?

texts: I've understand that outside of African, most ethnic groups carry some (4% or less) Neanderthal DNA.  So en masse, across all living humans, what percentage of the original Neanderthal genome is still alive in human decedents today?


texts:
Many hormones use 2nd messenger mechanisms, such as cAMP and cGMP, and also act on the same cells. For example calcitonin and PTH both use cAMP and have opposite effects.
How is it possible that the same second messenger molecule (cAMP) can have opposite effects on the same cells? Why are there more hormones compared to 2nd messengers - doesn't that reduce the uniqueness of each hormone? Shouldn't that make the function of any hormone using e.g. cAMP be the same as that of any other hormone using the same 2nd messenger on the same cell?


texts: Is there any evolutionary reason for why some organisms (wrasse) change their sex in adult stage?

texts:
In San Francisco, I saw this fish:

and quoting the aquarium's page:

  Part of the wrasse family, the California sheephead is a protogynous hermaphrodite. Simply put, all sheepheads are born as females, but eventually transform into males. Due to hormonal changes triggered by environmental and social cues, this fish can go from a reproductively-functional female to a fully-functional male.

I have never heard of something like this for any organism. Is this behavior unique?

But the real biology question is why they do that and not simply retain one gender throughout their life? In other words, what's the evolutionary advantage of such a weird approach?


texts: How to parse SCOP parseable files PDB residue identifiers?

texts:
I am trying to parse the SCOP parseable files, specifically dir.des.scop.txt ver 1.75. But, I have been facing problems with the PDB residue identifiers in the file. This is a tab limited file and the PDB residue and chain identifier is the 6th column which. An example of this identifier is A:1-28,A:77-837 for domain d1kk8a2.  Hence forward I'll represent that as domain_id (pdb_id chain&range). This particular example is straightforward, which means the domain d1kk8a2 consists of residues 1-28 and 77-837 of chain A of the corresponding PDB entry 1kk8. But some of them are unintuitive and like d3ckra1 (3ckr A:-2-385), what does the negative entry for the start mean? And this example d2p83b1 (2p83 B:61P-385), there is a P in the range (61P-385).

If you go to pdb website and search for the corresponding entries, then go to the sequence tab, you will see the alignment of the PDB chain and the corresponding SCOP domains. The ranges shown there correspond to the entries in SCOP, but it is difficult to make sense of it. Can someone please explain or provide some pointers. Thank you.


texts: Design primers for PCR from given DNA sequence

texts:
Given the sequence: 5’-ACTGACTATGTAGAA………GGCCCTAAGGGCCAA-3’ (1)

  You wish to do PCR of this dsDNA to add “overhangs” on the ends of it. On the 5’ end of you will put
  the restriction site for NdeI enzyme (5’-CATATG). On the 3’ end you will put the restriction site for
  MspI (5’-CCGG).

  Write the sequences for the “forward” and “reverse” primers to do this. Each primer should be
  16-18 nt, with 12 nt for hybridization and 4-6 nt for “overhang.”

I am a little confused as to how to write the forward and reverse primers for the sequence. From videos I have seen that I should write the complementary strand of my giving strand. Which would be:

3' -TGACTGATACATCTT........CCGGGATTCCCGGTT-5' (2)

Then from sequence (1) I should get the reverse primer and from sequence (2) the forward primer. However, this doesn't allow me to add both restriction enzymes because both primers would be from 5' to 3'.

Or should I simply take the given sequence and write the primers only from that? So that the primers would  be:

Forward primer:
3’-GGCCTGACTGATACAT

Reverse primer:
GGATTCCCGGTTGTATAC - 5’

where the bold nts are the restriction sites.

Thank you!


texts: Some monocots (such as palms) are impressively thick and massive, yet botanists maintain that they don't have secondary growth. Why do botanists say this?  How can it get so big without secondary growth?


texts: What's the exact meaning of and how to derive the coefficient of the path from sire to offspring?

texts:
According to Wright's Coefficients of Inbreeding and Relationship,

the coefficient of the path from sire to offspring is given as

$p_{o \cdot s}=\frac{1}{2}\frac{\sqrt{1+F_s}}{\sqrt{1+F_o}}$

But how to get this formula?

And what is the  exact　meaning of this path? It's the path from sire's genetype to offspring's corresponding genetype, or just from one allele in sire's locus to offspring's one allele in the corresponding?

Furthermore, Wright gives
$F_o=\frac{1}{2}r_{sd}\sqrt{1+F_s}\sqrt{1+F_d}$

From Wright's another paper Correlation and Causation we know
$d_{o \cdot s}+d_{o \cdot d}+d_{o \cdot \bar{sd}}=1$

in which

$d_{o \cdot s}=p_{o \cdot s}^2$,

$d_{o \cdot d}=p_{o \cdot d}^2$,

$d_{o \cdot \bar{sd}}=2p_{o \cdot s}p_{o \cdot d}r_{sd}$

Thus

$\frac{1}{4}(1+F_s)+\frac{1}{4}(1+F_d)+\frac{1}{2}r_{sd}\sqrt{1+F_s}\sqrt{1+F_d}=1+F_o$

$\implies F_s+F_d=2$

Since $F_s,F_d\le 1$,
we have $F_s=F_d=1$......

Incredible. But what's wrong with it?


texts: Are centrioles really absent in human neurons?

texts:
A booklet (issued by my school) claims,

  Centrioles, formerly believed to be absent in neurons, have been described in neurons and may be associated with the production and maintenance of neuro(micro)tubules in them.

I was under the impression that mature human neurons are totally devoid of centrioles.

Being something circulated at a school, it lacks niceties such as citations/references. I've done a spot of Googling, but that didn't yield anything confirming the claim in the booklet.

Q- As per latest studies/info. do (mature) human neurons really possess centrioles?


texts: Can anyone tell me what kind of tree this is? I took this picture today. It's in Iowa City, Iowa.


texts:
Previous research

A friend of mine shared a link of some beautiful fungi: http://imgur.com/a/Dii3H. I was intrigued by the curious critter below -- it seems to have honed the power of buckyball geometry, presumably much before we Humans ever did (search: Buckminsterfullerene to learn about a feat of chemical engineering).
Google reverse-image search almost got me the answer I needed, but no species name.
I've asked friends on Facebook with no answers yet.

Question

What is the name of this species of fungus?

Related Questions on Stack Biology

Here's a related Species Identification question of a fungus: Puffball mushroom species ID? (by @rg255)

EDIT: I'm an idiot... the Imgur had species names, thus answering my question, post-mortem. Thanks @skymningen for pointing that out.


texts: How does the body detect irreversible binding to receptors?

texts:
I have read an article on Wikipedia about irreversible agonists and antagonists. These permanently bind to a target receptor on a cell. However, the receptor protein is then internalized and recycled by the body after the binding occurs. How does the body detect when a protein has been irreversibly bound in such a way? Is there some pathway involved in that or are proteins simply regularly recycled by the body?

Article: https://en.wikipedia.org/wiki/Irreversible_antagonist


texts:
I was doing a practice exam paper and it asked for different 'forms of free energy'. I am a physicist rather then a biologist so 'free energy' to me means Gibb's Free Energy:
$$G=H-TS$$
But I cannot see how you would could have different forms of this. So is my interoperation of 'free energy' right and how can we have different forms of it?


texts: What is the significance in an alpha-helix being right-handed or left-handed?

texts:
Why is that often when alpha-helices are discussed, it is also mentioned their direction - right-handed (clockwise) or left-handed (anti-clockwise)?

I have heard that left-handed alpha-helices are usually less stable, but I'm sure there is more to it than that?


texts: Do supplements that increase pheomelanin change hair color?

texts:
People take supplements and ivs with things like vitamin c, glutathione and msm that, over months, results in lighter skin color. This has been explained by the supplements increasing pheomelanin and others decreasing tyrosine. I've seen other people explain pheomelanin causes red, pink and yellow tones and is more abundant in people with red, orange and blonde hair. With that being said, if these supplements have been shown to lighten skin color, why aren't there any cases, to my knowledge, of them changing hair color?
I suspect it is because the anagen phase of hair is longer than months. However, I've not seen any case of msm, glutathione or any supplements that results in increased pheomelanin production changing hair color over years. Can anyone explain this to me?


texts: What is the difference between copy number changes with and without allelic imbalance?

texts:
I require some clarification on copy number aberrations (structural gain and loss in chromosomes). From what I understand, gain/loss per se can be divided into two types.

Consider two alleles, A and B at the same locus on homologous chromosomes.

Allelic Balance: in one type of structural gain/loss, there is no resulting allelic imbalance; examples:

AB ==> AABB (duplication),
AB => -- (loss).

Allelic Imbalance: in the other type of structural gain/loss, there is resulting allelic imbalance; examples:

AB ==> AAB (duplication of A),
AB => -B (deletion LOH),
AB ==> BB (copy-neutral LOH).

First, is what I have described above correct?

Second, if it is correct, what is the biology underpinning these copy number aberration types? Are the mechanisms responsible for bringing about allelically-imbalanced CN change distinct from the mechanisms for bringing about allelically-balanced CN change? What are these mechanisms?

NB. I'm confining this to just copy number-related allelic imbalance.


texts: What does “energy transfer in cells” mean?

texts:
"ADP and ATP are involved in energy transfer in cells."
I know what is ATP and I know how ADP is formed, but I don’t understand what “energy transfer in cells” means.


texts: For most (if not all) people, their voice sounds a lot deeper when they've just woken, compared to how they sound during the day. This effect can easily last for a few hours, like for me today. What are the biological reasons for this? I've heard that it has something to do with relaxation of your muscles during sleep, but I'm not sure how that is supposed to work, and there might be other factors at work.


texts: Why is weight gain a symptom of Cushing's Syndrome?

texts:
Cushing's syndrome results from increased levels of cortisol in the body.

Cortisol as I understand it however, promotes the breakdown of glycogen and amino-acids in the process of gluconeogenesis, to increase blood sugar - opposing the action of insulin.

Why then does Cushing's syndrome lead to weight gain rather than weight loss?


texts: Can I estimate leaf temperature from air temperature? What other information would be required?

texts:
Physiological measurements such as respiration rate and assimilation rate depend on temperature.

Most papers report tissue temperature (e.g. leaf temperature for leaf measurements), although some report air temperature.

My goal is to compare measurements in the literature.  I use leaf temperature at time of measurement to adjust the rates to a common temperature. Currently, I assume that if leaf temperature is not available, it is the same as air temperature. (This is often assumed in papers where the leaf temperature was not measured).

Is there a way to estimate the difference between air temperature and leaf temperature? I can get fairly good estimates of other physiological traits (e.g. leaf thickness, albedo, stomatal conductance) as well as climate data (e.g. humidity, soil moisture content).

My model is:

  $T_{leaf} = T_a + X + \epsilon$

And I currently assume X = 0 in my calculations

Is there a better way to estimate X?

Under what conditions would X < 0? X > 0?


texts: Suppose that you place P generation wild type males and mutant virgin females in a vial and allow them to mate. You leave this vial undisturbed in the incubator for 12 days. Could you collect F1 flies for your inter se cross out of this vial? Why or why not?


texts: I saw these patterns on a hill. Which insect makes such a pattern?

texts:
Description of the location

It is in India
The place is 300-400 m above sea level.
There is no water body nearby.

Which insect makes these patterns?


texts: Interbreedability between current humans and his ancestors

texts: I want to know the first point of time in the past when genomes have diverged so far from modern human genomes so that they both (human and ancestors) are not interbreeadable anymore and can be seen as separate species.


texts: How does vasomotor and bronchomotor reactions equilibrate local blood flow to correspond local ventilation?

texts:
I am trying to find some figure(s) to explain this.
There is probably better name for "bronchomotor" reaction.
They seem to opposite terms and actually affecting same things (alveolar diameter/tone); one increasing, while the other decreasing.

I am been reading Pocock and Guyton but I am not happy in any any figures.

Which figures can you use to answers this question?


texts:
A man has the genotype AaBbCc, in other words he is heterozygous in three uncoupled loci on three different chromosomes. A, B and C are the dominant alleles while a, b and c are the recessive alleles.

1. How many gametes can he form?

The answer is 8 and I can see how you derive that by just manually writing each and every one down but what is the mathematical method to derive this? I tried permutations but none I came up with worked.

2. He has a child with a woman of the same genotype (AaBbCc) how many different genotypes can the offspring have?

Here the answer is 27. I'm not sure how they came to this conclusion either?

3. What is the probability that the offspring has the genotype AaBbCc?

This is about the time I start flipping tables because it seems to me that it's 1 out of 27. There are 27 different genotypes and this is ONE of them?!

But the answer is 1/8 as there's a 50% chance of Aa, Bb and Cc when mixing apparently so it becomes 1/2*1/2*1/2. Why isn't it just 1 of the possible genotypes?


texts: Is this aquatic plant duckweed or something else?

texts:
This plant has been growing in my pond for quite a time now. It multiplies in large numbers rapidly.
 Some told me it is duckweed or is it something else?


texts: Is it possible to Interpret Nerve Signals As to Where They Are Going In The Human Body And What Their Task Is?

texts:
I have recently watched some anime, (yes, anime, probably a huge cause to lots of questions asked on the internet), and it got me thinking. We can intercept nerve signals throughout the body, but could we interpret their task, as to whether they are meant to contract or relax a muscle, and their destination, as to which muscle they are meant to travel a signal to.

Extra Inspiration:
I have seen an article by Chris Brooker about the theory of intercepting optical nerves to benefit augmented reality, so it got me thinking, what if we could intercept all nerves in one go, the brain, but I realised, that's a stupid idea, they travel to the brain all over, so the next best location was the Central Nervous System (The Spine).

On top of Anime super inspiration, and some articles which helped further my theory, I thought more and more about how nerves travel around the body as impulses, so I theorised maybe they use different currents or charges to travel to different parts of a body, which brings me to my conclusion, is there anyone who would be willing to carry this experiment out? And then give me the results? If this is true we may be able to make a huge breakthrough in the virtual department, even if incorrect it can still be a starting stone for a new hypothesis.

However this entirely bases on the idea that all nerves start from one point on the cns, however the start to this would be to gain a test subject and patch a circuit into a nerve. on the circuit would be an ammeter and a voltmeter, and then have the subject move the muscles connected to the nerve.

The second step would be to find a lone point in the cns where all nerves touch or cross paths to identify the Sweet Spot (( ͡° ͜ʖ ͡°) I named it myself) and differentiate different nerves for different purposes.

Keep in mind this would be no small discovery, this would help engineer a better future in the virtual department, however this is only a small part to this, imagine being able to truly see or hear without the help of heavy machinery, or be able to walk with actual legs again, or be able to play catch with family again as this would engineer the greatest part to prosthetic engineering where we could actually move lots of different gears as if we contracted or relaxed a muscle.

If my hypothesis is completely off as my science is incorrect than please let me know. I currently do not have the facilities to go further into this as I am still in High School ((̿▀̿ ̿Ĺ̯̿̿▀̿ ̿)̄), and am busy with studies, but I hope I am correct and thus would have contributed to science which can help thousands of people everyday.

Please contribute to this topic even if it is criticising it.

Thanks,
IbnJalal


texts: Why are "itch signals" transmitted so slowly from the skin to the human brain?

texts:
In the second half of the BBC radio (and podcast) program Cats and Itch;
Discovery, The Curious Cases of Rutherford and Fry Episode 2 of 5 the phenomenon and origin of the "itch" and related sensations are discussed, with input from several specialists, including "Neuroscientist Prof Francis McGlone from Liverpool John Moores University and dermatologist Dr Brian Kim from the Center for the Study of Itch at Washington University. Yes, that is a real place."
Here is an unofficial transcription of a small segment starting at about 17:30:

Until quite recently, the same nerve fibers were thought to transport feelings of both pain and itch, from the skin to the brain. In 1997, a ground-breaking discovery revealed that itch has its own separate nerves responsible for that oh-so-familliar itchy-scratchy sensation. Now, if you accidentally lean on your “hot”, the sensation will travel through your fast pain fibers at 80 miles per hour; you can almost-instantly pull your hand away.
By contrast though, itchy signals crawl towards your brain at a sluggish 2 miles per hour, so once you’ve been bitten, it takes a while for the itching to begin.

Those quoted speeds equate to about 130 m/s and only 3.2 m/s, respectively.
What causes the "itch" fibers to transmit signals to the brain so slowly? Is there thought to be some evolutionary benefit to such slow conduction, considering that the speed of most signals from skin to brain are transmitted so much faster?


texts: Does the body lose energy or gain energy relatively when drinking or eating hot things?

texts:
Does the body lose or gain energy when drinking or eating hot things compared to more neutral temperature things?

On the one hand,
The body could somehow convert the heat energy into human usable energy,
And on the other hand,
The body heats up and needs to be cooled down, and this way it loses energy.


texts: Can oxytocin travel from one cell to another via gap junctions?

texts: Oxytocin is a 9-residue secreted peptide. As a hormone, can it travel through gap junctions, assuming that it is stored in pre-synaptic neuronal vesicles?


texts: How do biologists quantify "gene expression" in experiments?

texts:
I've read papers which contain statements such as "control of gene expression is critical in biological processes".

How exactly does one quantify "gene expression"? Isn't gene expression an umbrella term describing all of the mechanism by which DNA is synthesized into an organism's phenotype?


texts: Is chloroplasts per cell indicative of the photosynthetic power of a plant?

texts: Plant-A has on average N chloroplasts per cell. Plant-B has on average M chloroplasts per cell. If N > M, is plant-A more efficient in turning carbon dioxide into oxygen? Also, is it possible to see chloroplasts with a standard bright-field microscope?