texts:
Suppose we wind time back to the instance when life emerged on Earth and let evolution start over again, will human beings or any other kind of self-conscious animals evolve ultimately, inevitably?

Or do these sorts of animals just evolve as a result of some randomness processes in evolution, if so, what's the probability? Is it great or small?

If randomness does exist, then to what degree will it affect our ability to depict evolution? Will we still be able to describe the general trends of evolution, for example, the trend of more and more complicated animals evolving?


texts: Why do coronavirus cases graphs have a sinusoidal like shape?

texts:
Some screenshots from a canadian website:

See this sinusoidal shape? Why is it there? Shouldn't it be a single curve?
My main guess is when cases are counted: is it possible that they are counted something like every monday or so? I can't believe the virus progression really has sinusoidal-shaped curve.
It is not an error in the website, since other sources seem to show the same thing: worldometers, nbc news, and many others


texts:
I am somewhat new to evolutionary biology, having studied it on my free time as a computer science student.  There is one particular thing that has always bothered me for which I have not seen a good treatment, relating to adaptations to the environment with respect to genetic diversity.  If it is possible for a population to adapt to rapid environmental changes, and they don't have an adaptation for dealing with change directly (such as a complex brain), it seems to me that every generation must have present within them almost every possible environmental adaptation that the population is capable of expressing (including many irrelevant ones and a few relevant to the particular environmental challenge).  Otherwise, it may take too many generations to deal with a change, which may be disastrous for the population.

So my question would be: how does an evolutionary biologist explain the mechanics behind the ability for a population to adapt quickly?  Are most environmental changes slow or gradual enough that the population has a few generations to happen upon the mutations that will allow it to survive, and have generally been successful in this regard for 3.5 billion years?  Or, are a large majority of possible adaptations present in almost every generation, and just serve no purpose or advantage for most of the population if the provided "benefit" is unneeded (i.e., are effectively neutral)?  Or something in between?


texts: How does the body "know" how to metabolize foreign substances

texts: As a freshman biochemistry major, I find myself befuddled by our body's ability to perform complex chemical reactions to break down foreign substances. I can see how we would evolve explicit pathways to deal with substances we would find often in our environment of evolutionary adaptedness, but we also process things we would never have encountered before. How does the human (or any organism's) body do that without explicit programming?


texts: How is the probability of Rh type inheritance calculated?

texts:
I found somewhere on the Internet that, if parents are both Rh-positive, their children have 93.75% chance of being RH-positive and 6.25% chance of being RH-negative.

My question is: How is this calculated?


texts: Which hormones can cross the blood brain barrier?

texts:
Can hormones such as testosterone, aldosterone and estrogen cross the blood brain barrier?
I looked on Wikipedia and there no mention of it in the testosterone article. Through Googling around I also didn't find a list of which hormones can cross the barrier.


texts:
Imagine that complexity is measured by a positive number $f_n$.

If one has no prior knowledge about the positive number $f_n$ then from Bayesian theory one can assign $\log f_n$ an "improper" uniform prior over the range $-\infty$ to $\infty$.

A random mutation might increase or decrease the complexity of the offspring $f_{n+1}$. If we assume the offspring's complexity is likely to be close to the parent then we could simply model the random change in complexity by:

$$log f_{n+1} = log f_n + \Delta\ \ \ \ \  \hbox{with probability 0.5}$$

and

$$log f_{n+1} = log f_n - \Delta\ \ \ \ \  \hbox{with probability 0.5}$$

where $\Delta$ is some small number.

Such a random evolution will lead to the log of the complexity performing a random walk.

But now add sex.

Assume the complexity of a sexual organism is the average of the complexities of its parents.

$$f_{child} = \frac{f_{male} + f_{female}}{2}.$$

If one evolves the simple model now one finds that the complexity of the population grows exponentially.

Is this idea interesting or not? :)


texts:
What is a  genomic imprint? How does genomic imprinting take place?

If I say that "this" allele is maternally imprinted does it mean that the allele of the gene is passed only by the mother? If a pedigree is given, how can we identify whether the trait is paternally imprinted or maternally imprinted?

Please try to explain all this in as simple words as possible.


texts: What's the frequency resolution of the human ear?

texts:
I was thinking about audio compression (namely mp3), that "filters" out sound that we would not likely hear.

  The MP3 lossy audio data compression algorithm takes advantage of a perceptual limitation of human hearing called auditory masking.
  from: http://en.wikipedia.org/wiki/MP3

I've also checked the wiki entry for auditory masking, and found this:

  If two sounds of two different frequencies are played at the same time, two separate sounds can often be heard rather than a combination tone. The ability to hear frequencies separately is known as frequency resolution or frequency selectivity. When signals are perceived as a combination tone, they are said to reside in the same critical bandwidth.

My question is how much is this critical bandwidth or what's the smallest frequency difference we can perceive as two different tones, if you wish. Let's assume that both tones are equally loud, are coming from the same direction and distance and we are in a quiet room - so basically we eliminate as much noise and affecting phenomenons as possible.

As @ sanchises pointed out (thank you again!) in the comment section the frequency resolution is 3.6Hz between 1 and 2kHz. But since perception threshold is a function of the pitch of the sound I'd assume that the ability to resolve two tones would change with pitch too. Does anybody have any data on that? For example resolution X pitch graph.


texts:
In a small tribal population, the frequencies of two alleles A and a
  at a particular locus were 0.3 and 0.7, respectively. However, not all
  the individuals with genotype aa could live up to the reproductive age
  and the relative fitness of this genotype was found to be 0.5. The
  remaining genotypes had a relative fitness of 1. What is the expected
  percentage of heterozygotes among newborns in the next generation?

My answer is : 37 % but the answer given 43.52 %

I did the following : First I assumed the population to be of 100 individuals and then I counted the no of individuals with respective genotypes. Then I assumed that each person leaves 1 offspring except the aa ones which leave 0.5 offsprings and then I calculated the new genotype frequency from this.


texts: What is the genetic reason that this flower has petals of two different colors?

texts: I have two different varieties of the flower, portulaca: one is bright pink, the other is pure white with pink specks at the centre. Recently a flower bloomed which had 50% of the former and 50% of the latter: both traits in the same flower. Is this an example of co-dominance or is there some other reason for it?


texts: Is the water-splitting enzyme a component of photosystem II?

texts:
Can Somone answer a bit bizarre question which is that in light reaction . Photosystem uses enzyme to split the water up to hydrogen ions and electrons and oxygen.But is this water-splitting enzyme in or out of the photosystem 2(PS II)?
Great thanks


texts: Why are there no Nissl bodies in the axon?

texts:
What could be the significance of not having Nissl bodies (endoplasmic reticulum) in the axon hillock (a part of the cyton) and axon? Does it have something to do with the processing of action potentials?

What prevents Nissl bodies from entering the axon hillock even though they can enter dendrites (which are much narrower)?


texts: Does intermittent fasting promote neurogenesis through the same mechanism as aerobic exercises?

texts: I heard that intermittent fasting promote neurogenesis through the secretion of BDNF, I heard aerobic exercises does the same through BDNF. Now, I am wondering if there are other mechanisms through which aerobic exercises promote neurogenesis, but through which intermittent fasting doesn't.


texts:
Many breeds of domestic dogs seem to like burying food, presumably in preparation for leaner times.

Assuming that dogs evolved from animals similar to the modern wolves through a mix of natural and artificial selection, is this burying behavior novel in dogs, or inherited from wild wolves? Do wild wolves also habitually bury food, and return to their caches when hungry?


texts: Common properties of herbs in creating anaphrodisiac effect?

texts:
Recently came across Wiki article about anaphrodisiac herbs and other products.

An anaphrodisiac (also antaphrodisiac or antiaphrodisiac) is something
that quells or blunts the libido. It is the opposite of an
aphrodisiac, something that enhances sexual appetite. The word
anaphrodisiac comes from the Greek privative prefix ἀν-, denoting
negation, and aphrodisiac, from the Greek goddess of love, Aphrodite.
Reference

The article mentioned some of the herbs and plant related putative anaphrodisiacs like,

Marjoram (Origanum majorana) (Family: Lamiaceae)
Humulus lupulus (Family: Cannabaceae)
Heracleum mantegazzianum  (Family: Apiaceae)
Morton Arboretum  (Family: Salicaceae)
Vitex agnus-castus (Family: Lamiaceae)
Ruta graveolens (Family: Rutaceae)
Coriandrum sativum (Family:  Apiaceae)
Tropaeolum tuberosum(Family:  Tropaeolaceae)

I am not sure that is there any relevance in these claims that these herbs triggers anaphrodisiac effect.
The question is,
Is there any common alkaloid, aromatic hydrocarbons or any other chemicals present in these herbs which triggers the anaphrodisiac effects ?


texts: Is it fair to say that the majority of alleles of a typical diploid organism are homologous at each locus?

texts:
I'm trying to get an overview of when zygosity actually comes to bear in regard to the entire genome, the following statement represents my understanding so far...

  In a typical diploid organism, most of the genes/alleles on each locus are identical/homologous (say in the order of 95-99%) with the corresponding gene/allele on the other chromosome.
  When compared to the overall genome, it is only on a relatively small number of genes/alleles where the degree of similarity of the alleles for a trait becomes an issue.

So in other words would it be fair to say that, for a typical diploid organism, most of the genes on each chromosome are identical to their counterpart, it is only on a relatively small number where differences occur. e.g. most of the genes/alleles in a pea plant are the same and the resulting traits can be easily predicted. It is only a relatively small number of genes e.g. the genes responsible for flower color in a pea plant, or eye color in humans that the issue of zygosity, and using statistical techniques like Punnet squares etc comes play?


texts: When you blow through your nose while holding it closed to "depop" you ears, why do you sometimes feel it in your eyes?

texts: After your ears have "popped", for example on a flight, I heard you are supposed to hold your nostrils closed and blow through your nose to readjust the pressure to the normal level. Why do you sometimes feel a pop in the corner of your eye when you do this?


texts:
In this question we are examining a bacterial RNA polymerase that elongates at 20 codons per second.
Question 1: How long will this RNA polymerase take to transcribe the Lac Z gene at 3510 base pairs?

My answer: A codon is 3 base pairs so I start by dividing 3510 by 3 and then by 20 to get 58,5 seconds.

Question 2: Your bacteria can produce a Lac Z mRNA about every other second. How can you explain this?

My answer: I am very lost on this one. I thought that the mRNA would be as long as the gene so wouldn't this be 58,5 seconds not roughly 2 seconds??


texts:
As I understand it, the ejecta resulting from the K-T impact (also known as the end-Cretaceous or Cretaceous-Tertiary extinction event) re-entered the atmosphere all over the world; the heat from friction with the atmosphere raised the air temperature to a few hundred degrees C. All organisms all around the World were incinerated, except those that could bury underground or move into water.Now birds don't bury underground, nor do they   bury their eggs. So, how come birds didn't go extinct?

To clarify, I'm not considering the longer term cooling effect (which was in turn followed by a longer term warming effect due the CO2 dumped in the atmosphere). What happened just after the impact was that a sizable fraction of the entire volume involved on the collision would be on ballistic trajectories. Most of these would fall back to Earth, while a small fraction would escape Earth's gravity. Now, these ejecta actually contain a significant fraction of the total energy of the impact and almost all of that in then dissipated as heat when they re-enter the atmosphere. This leads to shock heating of the atmosphere to at least a few hundred degrees celcius, but much higher temperatures are also possible, see also this article.


texts: The role of GC content in promoting or hindering transcription

texts:
This is quite a specific question, and I'm hoping someone might be able to assist in a literature hunt I've been engaged in for ages.

I study some long bacterial operons, and have noticed that the GC% content at the 3' end drops significantly compared to the beginning of the operon.

I vaguely recall hearing (I can't remember if it was from a paper or a lecture or something), that lower GC (higher AT) content can promote transcription. This sounds plausible to me since it promotes strand separation (this is how replicon origins are often defined), but I've tried several times to find a paper that might demonstrate/attest to this. The hypothesis therefore, is that the distal ends of the operon might have lower GC in order to enhance transcription as the influence of the 5' UTR promotor sequences etc being to wane over a distance.

Has anyone ever come across such a paper or has any information to confirm or deny this? Information to the contrary (e.g. high GC reduces transcription) would also suffice.


texts: Why don't Australian magpies in Tasmania swoop at people?

texts:
I'm currently living in Tasmania (Australia) and I have noticed that Magpies don't swoop at you here, yet they do in other parts of the country.

Just wondering: does anyone know why?


texts: Could we transmit smells electronically?

texts: We can encode sound and images in radio waves and send them, but presumably there's some physiological reason that we can't easily make a picture or video of a smell. Could we realistically break smells down into "primary scents", in analogy with "primary colors" and encode the information for easy reproduction?


texts: Why is ab initio protein secondary structure prediction less reliable than alternatives?

texts: To predict secondary structure of proteins three types of Algorithms are used Ab initio, homology based and neural networks. Among these neural networks prove to be more accurate and give good results as compared to ab initio, especially when multiple sequence alignment and neural networks are combined the accuracy of results reach almost to 75%. My query is that what actually lacks in ab initio methods which reduced their sensitivity and specificity and lacks the ability to predict reliable secondary structures? (Some of ab initio based softwares that I have studied are Chau Fasman and GOR Method)


texts:
What is the smallest viable reproducing population, such as in a human population. By viable I mean a population which keeps genetic defects low (enough).

A very strongly related question: what is the expected number of generations a given population can survive?


texts: NCBI E-utility to Find Shortest Citation Path Between Two Publications

texts: I'm trying to perform a thorough review of Hi-C and RNAi developments and have found myself looking at publication A (2011) and publication B (2015). B doesn't cite A explicitly but I'm sure there are papers linking the two and I'd like to find them. Are there existing utilities to help with this? I've used NCBI E-utilities in the past but would prefer not to rewrite an application that already exists.


texts: How are Mono and Diglycerides metabolized without the Free Fatty Acids of Triglycerides?

texts: Having difficulty figuring out what the body does with ingested mono and diglycerides if the usual process of TAG metabolism includes the FFA released from the TAG returning to the MAG to recreate a TAG in the enterocyte, whereas with MAG and DAG consumption, those FFA don't exist. There are many studies (Nagao, 2000, Takatoshi, 2002 and others) confirming that DAG oil consumption leads to weight loss, which is seemingly obvious as the fat cannot be stored without the FFA getting repackaged into TAGs for storage in the adipose tissue. I have not found any studies on what actually happens to the MAGs in lieu of its normal course. I would much appreciate if someone could direct me to literature discussing this process or help me better understand it. Many thanks! Anyone?


texts: Deletion of codons at the start of a sequence in preparation for heterogeneous expression. Why?

texts:
I am reading a patent where they isolate a gene from cDNA constructed from RNA extracted from plant matter.

The subsequent step (in preparation for heterogeneous expression in E Coli.) puzzles me:

The codon optimization I can understand but this part confuses me "...remove the first 23 codons from the DNA sequence and replace [the start?] by the ATGGCT sequence."

Why would one remove a set of codons at the start of a sequence? How did they decide how many to remove Is there an obvious reason I am missing?  Also what is special about the ATGGCT sequence.

Any ideas why they would do this?

The start of the new sequence (1650 bp) looks like this:

atggctaccg ataatgacag ctctgaaaac cgtcgtatgg gtaattacaa gccgtccatc       60

tggaactacg acttcctgca gtccctggct acccgccaca atatcatgga agagcgccac      120

whereas the original sequence (1710 bp) was this:

atggattctt ccaccgccac cgccatgaga gctccattca ttgatcatac tgatcatgtg       60

aatctcagaa ctgataacga ttcctcagag aatcgaagga tggggaatta taaacccagt      120

Another point I am confused about is that 1710 - 23 x 3 + 6 is 1647. But the new seq. is 1650 bp. What gives?


texts: What do bloodsucking animals actually feed on?

texts:
A number of animals, including mosquitos, leeches, ticks and so on, feed on blood. And yet, at least in mammals, most stored nutrients can be found in body fat as fat, muscles and liver as glycogen and digestive system as undigested nutrients, leaving very little in the blood itself. Normal blood sugar before a meal is 70-99 mg/dL, which at the high end means blood contains roughly 3.8 kilocalories per liter. This means that to gather a single kilocalorie from blood glucose, it would take 26 mL of blood, more than any leech could reasonably hold. Estimating the mass of a leech at 20g and scaling down human caloric needs linearly, 2500 kilocalories per 70 kg, yields a leech caloric requirement of 0.714 kilocalories per day. By this estimation, a leech would need to feed at least once per day to meet its energy needs, and yet data from the American Museum of Natural History states that a leech need only feed once every few months. The same math holds for other bloodsucking animals.

So what in blood do bloodsucking animals actually feed on?


texts: Clatherin Mediated endocytosis is pinocytosis or phagocytosis?

texts:
This was a question in a test. Clatherin mediated endocytosis is which of the two: pinocytosis or phagocytosis?

Precisely what is the difference between the two and CME?


texts: Chlorine is usually mixed in water to make it safe for consumption. What is a safe quantity of chlorine that can be consumed? What are the side effects of chlorine and does this include hair loss? What are some common chemicals utilized for water purification? Thank you.


texts: Would this mushroom make the basil dangerous to eat?

texts: My sister is growing basil in a planter on her balcony. Recently this big mushroom started growing there. Obviously we're not going to take a bite of the mushroom, but would its existence make the basil dangerous to eat?


texts:
I was at the park lying on the grass and its the third time I have seen them, I used to think they were parasites when I was like 7. It is the very small brown worm on the green leaf. It moves by squiggling. It comes in different colors but same size.

http://postimg.org/image/ea3x2nw95/
http://postimg.org/image/zfawh9pr1/


texts:
Once placed in proximity to its future meal, how long does it take for the larva of a solitary parasitic wasp to begin feeding? I have several books on wasp behavior, but none address the time involved. An internet search also proved fruitless. I am asking out of curiosity and also to ensure accuracy in a story I am working on. I am sure it varies, I am just trying to get a general idea. For example, is it possible for larvae to begin feeding as soon as they are deposited?
(Edit: I added details to this question thanks to the first answer I received on this question)
(Edit: I've spent some more time looking into this and thought I'd share some information, should anyone be interested. Indeed, larvae can begin feeding within two days of being deposited. The larvae of Cicada-Killer Wasp (Sphecius speciosus), for example, begins feeding in 2 to 3 days, according to "The Strange Lives of Familiar Insects" by Edwin Way Teale. In "The Hunting Wasp" by John Crompton, the introduction sets a general range of 2 to 3 days, although I have read online of some wasp larvae taking longer.)


texts: Are surface area or volume conserved during cell division?

texts:
I am a student of physics of mathematics with very little knowledge of biology. Nevertheless, I am very keen on biophysics and I'm trying to learn the biological concepts that I need on the way.

I'm preparing now my bachelor thesis (regarding the physics of cell division) and my advisor has recommended me a paper of his where he studies some forces that are relevant in this process.

Under his analysis the constriction of the cell is independent of the area of the cell (the cells constrict on a similar fashion no matter which size they have, the only important parameter is the shape) and he considers several different scenarios. Two of those seemed plausible biologically speaking to me but I don't know if they happen or not in real life. They are to consider the surface of the cell constant during the process or to consider the volume to be constant (during the constriction of the cellular vesicle prior to the division in two new daughter cells).

Are any of these assumptions realistic? Does the area or the volume of the cell undertaking mitosis change drastically during the constriction of the cellular vesicle?


texts: How exactly does chemotherapy cause anemia?

texts:
I’ve been trying to figure this out for the past few hours but I still can’t find something as in depth as I’m looking for. So far all I’ve found is that chemo drugs kill bone marrow cells and some other drugs can damage the kidney which decreases red blood cell production, but I’m looking for something a bit more in depth.
From my understanding, there are multiple “groups” of chemo drugs (such as alkylating agents, antimetabolites, etc), so I assume there isn’t one answer which covers every group (unless, hopefully, I am wrong). I’ve read explicitly that some groups, like alkylating agents, are known to cause death in bone marrow cells. This also made me question if anemia/bone marrow cell death is a side effect from every chemo drug. If not, is it known which groups of chemo drugs are most likely to cause anemia and how exactly they do cause anemia (as in anything more in depth than “they kill red bone marrow cells”)? I’ve also read that some chemo drugs containing platinum can damage the kidney, but I wasn’t able to find how exactly it damages the kidney in a way that red blood cell production is decreased. I’m assuming this is due to a decrease in EPO production/secretion? If anyone has any relevant information/sources I would greatly appreciate it! Sorry if this is really specific and if this happens to be the wrong place to post such a question.


texts: What happens to the brain during meditation?

texts:
I've read several experiments on the internet according to which it is possible to reach a psychedelic state without taking any psychedelic drugs like DMT, LSD and other tryptamine derivatives.

It may sound stupid but I was thinking that the brain produces some minimal amounts of a psychedelic drug.
Maybe it is a tryptamine derivative (from the metabolism of the amino acid tryptophan, or from melatonin). I think that there is an undiscovered biological pathway for endogenous psychedelics (I can imagine DMT or 5-MeO-DMT).

What do you think about this? How can the brain go into a psychedelic state without taking any psychedelic drugs?


texts: We know that plant cells have dictyosomes instead of golgi but in my book it was written that plant cells have golgi apparatus?


texts: Why women have high Erythrocyte sedimentation rate?

texts:
Why ESR (Erythrocyte sedimentation rate)
1. higher in women
2. increases with age
3. increases in pregnancy, infection, malignancies

what I thought so far : since women are menstruating so there shall be some blood loss and this might be related to that.
For age I have no clue and in pregnancy might be related to fact the mass of rbc increases during pregnancy.

But is that right ? and what about  2 and 3 ?


texts:
One of the options is correct

Kidney can be taken from a dying person who has the
a) cessation of neurological function only
b) cessation of cardiac function only
c) cessation of respiratory function only
d) cessation of kidney function only

I think that answer should be b. as if heart stops working then the person is definitely dead. but m not sure if on the cessation of neurological/respiratory function, one still has chance of revivial. Moreover answer is given as A. I don't know how. Could it be that on cessation of cardiac/respiratory function, kidney gets damaged while not so in case of neurological dysfunction?


texts: Does "squinting" make you concentrate better on a logic test?

texts:
We have all had those moments of intense concentration on some tough exam, perhaps a college test or whatever...

Why is it that when we squint, it feels like we can focus and concentrate better on the test, and get answers more easily?

Do we actually get a better mental performance when we are squinting?  If so, why?


texts: Is there a normal human melatonin concentration to light level curve?

texts:
I'm looking for a graph or a curve that would show the typical concentration of melatonin in blood or saliva for humans over 24 hours. It would be good to know the photoperiod for the same human as well.

I know that melatonin release is inhibited by blue light, perceived through the retina, with melanopsin being the photopigment that signals suprachiasmic nucleus to suppress melatonin release. This is why it would be great to see melatonin data alongside light exposure data.

Thank you for any hints on where I can find such information!


texts: Do lunar rhythms have impact on human biology, if so, how?

texts:
I'm approaching this question from the circadian rhythm perspective. A circadian rhythm is a 24 hour cycle. While doing research on deep sea circadian rhythms, I found this abstract which seemed to imply that there are some kinds of lunar rhythms (about a month long cycle). Lunar Rhythms in the Deep Sea: Evidence from the Reproductive Periodicity of Several Marine Invertebrates:

  While lunar rhythms are commonly documented in plants and animals
  living in terrestrial and shallow-water environments, deep-sea
  organisms have essentially been overlooked in that respect.

What do the authors mean by the lunar rhythms? The roughly month long menstrual cycle, or are there other ways that the moon actually influences animal/human biology?


texts:
In plasma and other body fluids, miRNAs can be found. They not only originate from dying cells but also from active secretion and are usually 'packed' into vesicles/lipo-proteic structures (i.e. exosomes) protecting them from the action of ribonucleases. Thus, miRNAs in plasma are very stable, offering diagnostic opportunities.

My question is whether they may also have a functional role. Exosome transfer between cells has been demonstrated, so it is likely that miRNAs can be secreted by one source cell and reach a target cell, similarly to how hormones works. However, this has not been quantitatively assessed. Is the concentration of miRNAs in plasma known? Is it sufficient to hypothesize functional regulation of gene expression in target cells?


texts: Are vegetables really needed in our diet?

texts:
I want to believe that eating vegetables is necessary even when one takes
vitamins, but I can't find any medical evidence for this.  To make my question
specific, suppose a study on twins were done in which one ate anything they
wanted and the other was limited to just potatoes, chicken, vanilla ice cream,
and water, but both took vitamins (with 100% RDA from the 2015 guidelines).
What statistically measurable difference will you see?  Will the twin with the
free diet live much longer on average?  Is there a published medical study
(perhaps on mice) showing this benefit?


texts: Does the amplitude of action potentials vary among species?

texts: I would like to ask if the amplitude of action potential in animals(for example zebra finch or other bird) differs from the amplitude of action potential in humans which is approximately 70mV.


texts:
I'm a total novice when it comes to biology, and I'm really just looking for an answer to a question that has been posed to me by people who deny evolution fervently.

Evolution dictates that we've gone from simple, single cell organisms to complex, multicellular organisms. If we consider the hand, for example, the hand is made up of various cells. Those cells are created according to DNA, which acts like a cell-level instruction manual.

Where are the "instructions" for where those cells go? I.e Where are the instructions that state that various cells have to line up in a thin, long, appendage structure to form a finger, or hand.

This isn't a particularly difficult question, I imagine. If it's been asked before, apologies. I don't know any of the technical terminology; this is just something that I would like to learn about.


texts: I am trying to get a pdb file that contains a single atom, it doesn't matter if it's Hydrogen or another atom. How can I obtain this? Are there any pdb files with just a single atom available to download? Or do I have to take an existing molecule and remove the atoms manually?


texts: Similarly, what makes a wet down comforter so stinky? Why do they make no smell except when liquid is added?


texts: How do I perform recurring pattern mining or regular expressions of nucleotide sequences?

texts: I am interested in performing nucleotide sequence pattern-mining (regular expressions) which is 12 characters (sequences) in length from a dataset. Is that possible to script using MATLAB?


texts: What is the difference between phylogroup and subclade?

texts:
Looking for clarification in terminology, examples would be greatly appreciated!

Not sure how this is off-topic. It is a general question about the difference between biological concepts defined in the field of bioinformatics.

"Questions are from students, academics and active researchers in biology and closely related fields, including:

general questions about biological concepts
questions about the biological mechanisms behind medical conditions
questions about techniques in a biological or biochemical laboratory

Questions on interdisciplinary subjects like bioinformatics are also welcome, as long as they focus on the biological part of the subject."


texts: What is the energy source for adipocytes?

texts: Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes?


texts: Why is cholera toxin added to certain culture media?

texts:
I was reading an article [1] where they cultured SEB-1 human sebocytes in DMEM F12 + FBS + EGF + adenine + hydrocortisone + insuline as well as cholera toxin. Why is cholera toxin added to the media? Will the toxin not initiate some kind of unwanted immune response?

https://www.ncbi.nlm.nih.gov/pubmed/25647437/


texts: Once neurotransmitters bind to its receptors, how does the post synaptic neuron "know" when to start a new action potential?

texts:
My textbook seems to gloss over this subject. Once the post-synaptic receptors are activated, do they cause particular ion channels to open, letting positive charge into the cell and inching the neuron closer to the AP threshold?

Also, does the action potential start in the dendrites or the axon? Does the cell body experience membrane voltage? If so, how does the charge get past all the miscellaneous organelles in the cell body? Does it have like a special charge pipe to go down? Or do the ions just float past the organelles?


texts:
I don't know if this is off topic at all, but there are a lot of things that humans tend to consider beautiful which other animals in nature also seem attracted to. For example, bees pollinate the most vibrant flowers. Birds of Paradise appear to demonstrate a selective advantage to looking pretty. Peacocks flaunt their looks. Songbirds sing beautiful melodies. Butterflies are amazing. Some spider species have bright colors and perform cute dances. It seems like these examples demonstrate an evolutionary advantage not just for things that stick out from a crowd but also that look good to us humans.

So I guess my question is, is beauty universal? Are there aesthetic characteristics that are attractive to all these different kinds of animals, that would signal something good for others to see, and that different animals including humans would universally recognize as being nice?


texts:
My very basic understanding is DNA gets transcribed into RNA by effectively replacing thymine with uracil, then RNA is translated to make proteins. Looking at it from an engineering perspective, it would appear that, while the RNA to protein translation is non-trivial, the DNA to RNA transcription process is rather redundant: As it's just a simple replacement, why not start with RNA in the first place? My assumption therefore is that there is something about the RNA molecule (e.g., too reactive, too unstable, etc.) that requires it to be put in "cold storage" as DNA.

I don't have a background in genetics or biology, so could someone ELI5 why DNA is needed?


texts: Do you have nerves on the outside of your skull?

texts: I have a spot on my skull that feels like a nerve or blood vessel. I know that there are many to the brain, however, it is the only one I have ever felt. So do we have nerves or blood vessels on the top or outside of the skull?


texts: Why do most animals never seem to evolve over millenia?

texts:
People often say, including those with extensive knowledge in biology, that a certain species of animal will evolve in one way or another:

From changing environments.
Mutations.
Possibly even genetic engineering from human animals.

My question lies in the fact that, aside from the latter option, why haven't any differences in animals'(except humans) markup, morphology, intelligence, DNA, behavior, or any habits changed over thousands or (possibly millions) of years?

A cockroach has had the same behavior it has today more than 10 million years ago, and there have been no advancements in the species in the slightest bit.

It makes you question evolution, because why don't other animals (like cockroaches) have any changes over 10+ million years, yet humans, like me and you somewhat, have, in a relative period of time similar to the linked geological period above, evolved from spear tossing hominids into someone brilliant enough to even ponder this question.

If modern humans are the result of mutations in genes, why has no one species over the course of hundreds of millions of years been fit enough, or advanced mentally as we have, or even in any slightest bit?


texts: Distance to source populations and/or environmental gradients?

texts:
How do you disentangle the effects of distance to source populations and environmental gradients when the environmental gradient occurs in the same direction as the source population?

For example, if I have a regression model with species richness as the independent variable and distance to source population and pH as significant dependent variables, how do I know which is the driving factor?


texts: Why cytotoxic T cells don't kill dendritic cells when they present antigen?

texts:
When a cytotoxic T cell (CTL) recognizes a peptide presented in the MHC-1 of a dendritic cell (APC), why it doesn't kill this cell?

I know that initially, in the lymph node, the T cell is inactivated. But eventually it becomes activated and travels to the tissue, where it again finds APCs presenting the offending antigen. So why doesn't the CTL kill the APC at this point?

Moreover, not all MHC-1's of the dendritic cell present antigens from phagocytized cells. Some MHC-1's present peptides coming from the dendritic cell itself, so that if the dendritic cell itself becomes infected with virus or bacteria, it can be killed by a CTL that recognizes the peptide. So in this case, the CTL does indeed kill the dendritic cell.

So my question is, when exactly does the CTL kill the APC? How does the CTL knows that should or shouldn't kill the APC?


texts: Questions about Cohesin - what does the ATPase domain do, and any suggested PDBs to look at?

texts:
I've been reading about cohesin lately, and I'm confused about the head subunit interactions.  I've read a few papers, and also found this nice figure from wiki that demonstrates the crux of my question (note: SMC here corresponds to Cohesin, or am I mistaken?  I'm pretty sure this is correct, or pretty much correct):
From reading around, I'm aware generally the head subunit is an ATPase, yet from this diagram (and from the typical putative "use" of Cohesin in TAD maintenance), I'm not sure what exactly is the ATPase motif so useful for, it seems that the ATP is sort of "glueing" the the two head domains together, but that seems opposite of what ATPase would typically do, ie catalyze ATP -> ADP.  This makes me think I'm just misunderstanding something, and wondering what is the function of the Walker A/B ATPase motif.
Also, I'm wondering if there are any nice PDB files that show a cohesin loop, or elsewise are generally the most instructive about Cohesin.  I've searched through a few, but would like more informed advice about some good structures, and maybe why they are nice.


texts: Coefficient of Inbreeding - implementation issue

texts:
The formula for the coefficient of inbreeding is as follows...

I have a family tree going back 9 generations. Say I find a common ancestor X in the 4th generation on the mothers side and in the 5th generation on the fathers side. I can work out that constituent of F... but what do I do about all the ancestors of X (they will all also be common ancestors). Do I also work out their values and add them to F?... or do I ignore them? The descriptions of the COI I have seen do not make this clear.


texts: What are these flower like cells in the photo attached?

texts: I am a student of BSc. Zoology... I was doing a TC of RBC of my blood when I encountered these strange flower like cells. Are they lysed RBCs ? If so, why are they so geometric in shape ?


texts:
I have read that DNA can be concentrated by addition of isopropanol.

What does "concentrated" mean? What does isopropanol do on a molecular level to concentrate DNA?


texts:
With the acceptance of being a little overweight

I hear of people saying they were born morbidly obese and it was genetically passed on. I'm aware being so obese leads to countless health issues, yet we have people defending fat shaming and the likes. Is the excuse of having 'obese' genetics scientifically justified? Do people have genetics that make them ridiculously fat? Alongside, would this simply be down to the diet of the person from a young age?

Thanks.


texts: What current evidence supports the use of hydroxycloroquine used as a prophylactic for (corona)-viral infections?

texts: I've also read comments from doctors suggesting that hydroxychloroquine has been studied in the past as a potential prophylactic for viral infections.  A search through US clinical trials yields many results which mention this drug in connection to lupus, arthritis, and cancer.  But I have yet to find completed clinical trials which revolve around viral infections - does this exist somewhere or has this never been studied?


texts: Why is there now only one Salmonella species?

texts:
Once upon a time, I chanced upon an old microbiology book that detailed the rather colorful world of enterobacteria. Salmonella in particular stood out, as it seemed there were a lot of species: typhi / typhosa, paratyphi, gallinarum, typhimurium, choleraesuis, and quite a bunch of others that I have now forgotten.

Flipping through a newer book, it now seems that all of these "species" were collated under choleraesuis (and now more recently enterica), with all those species being demoted to "strains" (or maybe I should use the current term of art, "serovar"). Unfortunately, the book didn't give much in the way of explaining about this merger.

So, why is there now only S. enterica? If "S. typhi" is a mere serovar, how come the species name is still used in the literature?


texts: Strange Black-Brown Insect Identification

texts:
Interesting Insect from Singapore. Around 0.5cm. Has 2 tiny pinchers at its tail. Insect is black for most part.

Please zoom in on scotch tape:


texts: Found an unknown species, whom should I contact?

texts:
My father has found a very queer looking insect. He'd been watching it for over half a year on the tree right next to our house  and in all this time hasn't been able to find anything like it on the internet. Yesterday it died, and we found it on our porch, dad's put it in an air-isolated box for identification, please let me know if you are interested. We can send a picture of it for you via email or any other provided way, or please let us know what we should do it and whom we should contact. We live in Sydney.

Thank you, best of luck in everything!


texts: Is artificial selection a mechanism of evolution?

texts:
From whatever I read have seen that the mechanisms of evolution are

natural selection
mutation
genetic drift, and
gene flow

But artificial selection is often taught like a separate subtopic, but why isn't artificial selection also considered a mechanism of evolution?
Doesn't it work the same as natural selection, it's just the cause that is different?


texts: How are mitochondrial ATT (Ile) start codons translated as Methionine?

texts:
In some vertebrate species, some mtDNA start codon sequences are ATT but these are translated as Methionine rather than Isoleucine. What is the mechanism for this non-standard translation?

The main example below is in a bird, blue crane (NCBI Genbank excerpt below). The NCBI data give the standard note on completion of the stop codon but there is no note about modification of the start codon. We have confirmed this ATT start codon from PCR-Sanger sequencing an independent sample. There are similar cases in other vertebrates (Aves, Squamata, Amphibia) such as ND2 in Goggia geckos (example 2 below, also independently confirmed by Sanger sequencing. In this genus the start codon DNA varies from ATT to ATA or ATC: 50/59, 6/59, 3/59). I think I have seen this in other mtDNA genes. In many other birds and reptiles ND2 starts with ATG.

Are these modifed post-transcription to ATG? If so how?
Could they reflect a variant of the mtDNA code where AUU = Met? Or where any AUX codon is recognized as Met.

Example 1. ND2 from Blue Crane (NCBI Genbank refseq excerpt)

LOCUS       NC_020572              16696 bp    DNA     circular VRT 18-APR-2013
DEFINITION  Anthropoides paradiseus mitochondrion, complete genome.
ACCESSION   NC_020572
VERSION     NC_020572.1
DBLINK      Project: 193816
            BioProject: PRJNA193816
KEYWORDS    RefSeq.
SOURCE      mitochondrion Anthropoides paradiseus (blue crane)
  ORGANISM  Anthropoides paradiseus

 gene            3970..5008
                 /gene="ND2"
                 /db_xref="GeneID:15088361"
 CDS             3970..5008
                 /gene="ND2"
                 /note="TAA stop codon is completed by the addition of 3' A
                 residues to the mRNA"
                 /codon_start=1
                 /transl_except=(pos:5008,aa:TERM)
                 /transl_table=2
                 /product="NADH dehydrogenase subunit 2"
                 /protein_id="YP_007624320.1"
                 /db_xref="GeneID:15088361"
                 /translation="MNPHAKLIFLTSLVLGTTITISSNHWMSAWAGLEINTLAIIPLI
                 SKSHHPRAIEAAIKYFLVQATASALVLFSSMINAWSTGQWDITQLNQPMPCLLLTTAI
                 AMKLGLVPFHFWFPEVLQGSSLTTALLLSTVMKFPPITILFLTSHSLNPALLTSMAVA
                 SAALGGWMGLNQTQIRKILAFSSISHLGWMTIIIMYSPKLTLLTFYLYSLMTITVFLT
                 LNTTKALKLSTMMITWTKIPTLNATLMLTLLSLAGLPPLTGFLPKWLIIQELTKQEMT
                 TAATIITMLSLLGLFFYLRLAYYSTITLPPNSTNHMKQWHTDKSTNTLIAIFTSLSAL
                 LLPLSPMILTII"

 3901 agtagagtca gctaaaaaag ctatcgggcc cataccccga aaatgatggt ttaacccctt
 3961 cctctacta**a tt**aacccaca tgcaaaacta atcttcctca caagcctagt cctagggaca
 4021 accattacaa tctcaagcaa ccattgaata tcagcctgag caggcctaga aatcaatact
 4081 ctcgccatta tccccctcat ttcaaaatcc caccacccgc gagccatcga agccgcaatc
 4141 aaatatttcc tagtacaggc aaccgcttca gcactagtcc tcttctcaag tataatcaac
 4201 gcatgatcta caggacaatg agatattacc caattaaacc aaccaatacc atgcctttta

Example 2. ND2 in Goggia (Gekkota, squamata) NCBI nucleotide locus ref.

LOCUS       KF666817                1424 bp    DNA     linear   VRT 09-SEP-2014
DEFINITION  Goggia lineata voucher MCZ R184778 NADH dehydrogenase subunit 2


texts:
I've had an Araucaria tree in my garden for more than 30 years.
Today a fruit fell off the tree. It looks just like this one:

I want to know if it is toxic?

Can I eat it? If so, how?


texts: Are VCF headers supposed to change over time?

texts:
VCF headers describing the content of the INFO field are supposed to give additional information about a variant.

Example. A VCF file can be annotated against genomic variant databases such as dbSNP or ClinVar. The annotations such databases add to the file are described in the headers.

For instance, the CLNSIG field (taken from ClinVar) describes the clinical significance of a variant. Such field description is contained in the following header:

##INFO=<ID=CLNSIG,Number=.,Type=String,Description="Variant Clinical Significance, 0 - Uncertain significance, 1 - not provided, 2 - Benign, 3 - Likely benign, 4 - Likely pathogenic, 5 - Pathogenic, 6 - drug response, 7 - histocompatibility, 255 - other">

As reported in the field definition, the set of values it can take changes over time:

  Other non-standard terms are also used to meet submitter needs. ClinVar plans to add standard terms for other scenarios (e.g. somatic, pharmacogenomic, and mitochondrial variants) when they are available.

Do you know if this is a standard condition? Are headers supposed to change a lot over time? Is this condition valid only for clinical annotations (such as the ones provided by ClinVar), or something that is supposed to be considered for every annotation?

Thank you for your help.


texts:
When I checked it seemed trivial to answer: yes, all mammals can swim. But research on the internet provided different information. I found:

people and primates cannot swim, but can be taught how to swim
giraffes can't swim
someone claimed elephants can't swim, but this video ad shows the reverse
porcupines nor rhinos can't swim
at least some bats can swim, but according to this source there's insufficient data.

Of each hit, I found other hits that claimed the reverse, sometimes with proof. Common sense tells me all mammals can swim, but is this true?


texts: Why similarities among organisms led scientists to believe that organisms are evolved?

texts: Theory of evolution states that organisms are evolved into other more advanced ones over time because there are some traits in modern organisms resemble with organisms existing before (from fossil record). But it might be possible that each organism has created independently of each other. why similarities mean evolutionary relationship?


texts: Can non-carbonated energy drinks boost alcohol intoxication?

texts:
I just read news article about

banning caffeine in alcohol drinks and
about that energy drinks increase the urge to drink alcohol.

Energy drinks cause sugar intoxication - answer about it here in the thread Decreasing the alcohol proof and faster in hangover, why?.
Sugar dehydrates faster as well as causes a cascade of hormonal changes that are more immediately troubling than the alcohol.

I want to understand why energy drinks boosts you to drink more alcohol.
This suggests me that

malaise (caused by energy drinks) can be improved shortly by alcohol drinks

by some unknown mechanisms to me; and this can be the reason why people like to drink more alcohol after energy drinks.
I think that the mechanisms are related to some cascade which I do not know.
This mechanism can lead to improvement in the dehydration very shortly

by acting on the membranes of the cells
or by stabilising the architecture of the endothelium i.e. stabilising the hormonal changes.

My conjecture is that the alcohol can affect on the secretion of the substances from endothelium (EDRF, EDCF).
There are three types of substances secreted by the endothelium

NO
Endothelium hyperpolarising factors
Endothelins

So sugar intoxication causes changes in the endothelium architecture which alcohol intoxication reverts shortly back which boosts people to drink more alcohol to recover from the malaise caused by the energy drinks.

How can non-carbonated energy drinks boost alcohol intoxication?


texts: Can pseudogenes be transcribed into mRNA and translated into functional proteins, or should they be regarded as functionless mutated genes?


texts: Chorophyll and photosynthesis in plants with coloured leaves

texts:
Do plants that have only coloured leaves (e.g. ‘ornamental’ plants) contain chlorophyll and perform photosynthesis?

If they don’t, how do they obtain energy and metabolic intermediates?


texts: What is the water and fat composition of the human brain?

texts: Everywhere I look online says the brain is about 60% fat. But when it comes to water, I see numbers like 70-75%. One webpage even makes both those claims back to back! That doesn't make any sense. So what is it, really?


texts: Under what circumstances does Batesian mimicry evolve?

texts:
Batesian mimicry is a form of biological resemblance in which a noxious, or dangerous, organism (the model), equipped with a warning system such as conspicuous colouration, is mimicked by a harmless organism (the mimic). An example would be unrelated species such as Myrmarachne plataleoides, the spider, and the weaver ant Oecophylla smaragdina.

Given that evolution is a random process that doesn't have any pre-defined targets the probability of such convergence in evolutionary history should be nearly zero. My argument is that the search space for a 'nearly optimal' Batesian mimic would be too large and hence any search algorithm would be unable to avoid the curse of dimensionality. Even the sampler, which would
need to sample from a wide variety of valid phenotypes in the parameter space would run into serious problems.

The problem of the curse of dimensionality for optimal sampling can be intuitively explained in the following way:

Let's say you have a straight line 100 yards long and you dropped a penny somewhere on it. It wouldn't be too hard to find. You walk along the line and it takes two minutes.
Now let's say you have a square 100 yards on each side and you dropped a penny somewhere on it. It would be pretty hard, like searching across two football fields stuck together. It could take days.
Now a cube 100 yards across. That's like searching a 30-story building the size of a football stadium.
The difficulty of searching through the space gets a lot harder as you have more dimensions.

Here are additional points to clarify what I mean:

My question is whether the Batesian mimic would need to initially be quite similar in morphology to the different species that it's converging to in morphology. In mathematical terms, if the parameter space for the visible morphological features is $(x_1,x_2,...,x_n) \in \mathbb{R}^n$ then convergence is probable if and only if the initial condition lies in a small enough neighborhood of the solution $(q_1,...,q_n)$.

One of the features of the fitness function is that I think there should be exponential payoffs in terms of reproductive success near the solution $\vec{q}$. Further, I think there are probably other very important environmental factors that might lead to such convergence. An arboreal jumping spider of similar size that shares the same environment as leaf-cutter ants is a good example. They would already have similar color among other features in order to blend in the same environment.


texts: Why does the sex of the parent species determines the species of a hybrid offspring

texts:
I've read a little about hybrid animals, and have been amazed by the fact that the sex of the parent species determine the species of the offspring, in some hybrids.
A male horse and a female donkey will give birth to a Hinny, while a female horse and a male donkey will give birth to a Mule.

The same goes for tigers and lions, male lion and a female tigress will give birth to a Liger, while a male tiger and a female lioness mating will result in a Tiglon

I thought that the only difference between the male and female reproductive cell's DNA code is the X-Y chromosome that determines gender, not differences that can define the phenotypical result of the offspring. Why does this happen?


texts: Do Termites and Silverfish metabolize cellulose the same way?

texts:
I am fascinated with silverfish and would like to understand more about their metabolism.
I learned that they can survive on a diet of cotton which is nearly pure cellulose. Do they metabolize cellulose in the same way as termites?  Or do some insects have different metabolic pathways for cellulose?


texts: How do big cats perceive objects, specifically vehicles?

texts:
Right so we have been on safari in South Africa recently and before encountering big cats (lions) we have been told to hold still and not reach out beyond the boundaries of our safari vehicle because the cats would see it as uninteresting "object", unless something sticks out or moves.

Having a bit of background in biology I tried to map this to a more "scientific" explanation but wasn't successful so far. How would you describe the cognitve perception of vehicles by big cats (or lions specifically)?


texts: Why do humans have eyebrows? It seems that it isn't necessary but only humans have them, correct? So what is the use of them for humans? I hear that they protect our eyes. However, isn't that what eyelashes do? What other functions do eyelashes have?


texts: Thank you for replying my question..and sorry for my broken english (https://i.stack.imgur.com/5GXs5.jpg)


texts: Doubling the concentration of extracellular calcium hyperpolarizes a neuron. Why?

texts:
I was doing some back of the envelope calculations to try to answer this question in more mathematical terms. Essentially the question states: Why does increasing the extracellular potassium concentration depolarize a neuron, while increasing the extracellular calcium concentration hyperpolarize the neuron?

My initial thought was that there is a change in the equilibrium potential for each ion. Working this out however I realized I was wrong in my reasoning; my math proved me wrong.

Doubling the concentration of extracellular potassium makes the equilibrium potential of potassium 17.8 mV more positive. For calcium, it increases the driving force by 8.9 mV (based on room 300 K temperature). What this means to me is that both will cause the resting potential of the neuron to become slightly more positive, though calcium less so.

This is indeed obvious: adding more positive ions to the outside of the cell increases the driving force for that ion, and assuming there is any conductance (albeit small) then there will be some depolarization of the neuron.

This makes me think that this is not a phenomena explained by a neuron at rest. Some other mechanism is responsible for increased extracellular calcium causing the neuron to hyperpolarize.

My possible guesses:

If the calcium concentration is doubled, then the driving force for calcium increases, so there is more influx of calcium and thus the internal calcium concentration will increase. Because the concentration of calcium ions on the inside was previously near zero, now that internal concentration will rise to be some significant number, thereby hyperpolarizing the neuron.
The internal concentration of calcium rises slightly, but instead of (or perhaps in conjunction with) lowering the resting potential directly, there is more activation of calcium-activated potassium channels, thus raising the conductance of potassium ions, and thus ultimately hyperpolarizing the neuron.

Am I on the right track or am I missing something?


texts: If a gene is located on the X chromosome, does that mean males are never heterozygous for these genes?

texts: As said in the title I am a little confused on the idea of traits located on the sex chromosomes. The example we worked on in class was haemophilia, a recessive trait located on the X chromosome. Does this mean males only have one allele to choose from while females have two? Does this mean that only females have the ability to be heterozygous in sex linked traits?


texts: Why does histamine release in Type I hypersensitivity help in case of parasites?

texts:
The IgE system exists because the same events which lead to often-life threatening complications of allergy, in presence of parasites are helpful in their elimination.

The tissue injury mediated via this hypersensitivity (type I) occurs due to the mediators released by mast cell degranulation due to IgE being synthesised in atopic individuals towards normal environmental particles. The effects are also due to further immune cells being recruited by the mediators. In case of parasites, this IgE is supposed to help in their elimination and not cause tissue injury, justifying its evolution as a defence mechanism.

How does this happen? If release of the mediators is a part of the pathway, even if the degranulation is localised in the vicinity of the
 parasite, the mediators will spread systemically or atleast in the
 nearby tissues with the same consequences as in the case of
 non-parasite activation of these events.

What then is the ultimate cause beneath there being tissue injury if the stimulation is unintended but there being none when the stimulation is directed and intended? Or is there some injury in the latter case also, in which case the classification of this response in absence of a parasite into hypersensitivity i only because there is no positive effect in this case, while there was some benefit accompanying the deleterious effects in the former case? Is the presence of a parasite and possible localised degranulation the only difference between these cases?


texts: Correct term for initially neutral mutations that subsequently cannot be reversed

texts:
Can anyone tell me what the correct name is for a neutral mutation to a protein that occurs when that mutation becomes "locked in" due to a subsequent mutation?

For example: mutation A is neutral initially and can be reversed with no deleterious effects, but after mutation B, the reversal of mutation A would now become deleterious. What is the correct terminology for a mutation of A's type?


texts: variance in zygotic gene expression across species

texts:
I found this review on the Maternal-to-Zygotic transition (MZT), describing how developmental control switches from maternally deposited RNAs to zygotic expression. I was struck by figure 1, and the apparent difference between viviparous and oviparous life histories.
My maybe naive question is, Could the sharp increase of zygotic expression reflect conflict between the maternal and zygotic genomes?

MZT review


texts: Why are nosebleeds easier to get in the winter?

texts: I understand it probably has to do with the dry air, but what does dry air do to make nosebleeds so easy to get? For example, even gently blowing your nose can cause a nosebleed for some people during the winter.


texts: Why are our bodies created to itch when histamine is released by our immune systems?

texts: Why do bug bites and cuts itch when scratching them clearly doesn't help us survive? Did our early ancestors need to rely on this itching sensation, or is it just that the receptors for itches just happen to be stimulated by histamine?


texts: Why outgroups are supposed to be ancestral?

texts: I was reading about phylogenies and found many literatures said that outgroups contain the ancestrial trait, but why is that? Aren't they also experiencing the same amount of evolutionary time and (presumably) changing their characters as well?


texts: Distribution of genotypes after adverse selection

texts:
I am doing some research into Mendelian genetics and came across this phrase called adverse selection.

I found a few questions but I am unsure of the calculations. For example given a distribution

  [0.36 0.48 0.16]

it is stated that 25% of individuals with Aa(middle) genotype dies. The distribution changes to

  [0.4091 0.4091 0.1818].

I initially thought to just take off 25% of the middle becoming 0.36 and equally distributing the 0.12 change to the other two geneotypes. Can someone explain how they did this computation.


texts:
In this publication (PDF) I encountered the following word:

  Binding of rupatadine to histamine H1 receptors isolated from the
  guinea-pig cerebellum and lung was demonstrated by inhibition of
  3H-mepyramine binding; equilibrium inhibition constant (affinity) [Ki]
  values were 26–256 nM in the various experiments. Binding was
  time-dependent and pseudo-irreversible. Rupatadine was ~7.5 and
  10-times more potent than the structurally-related anti-histamines
  loratadine and fexofenadine. H1 receptor occupation by rupatadine in
  guinea-pig cerebellum and lung after oral (PO) dosing was relatively
  rapid (with maximum binding evident at 2–4 hours post-dose) and
  dose-dependent; low or no binding was seen at 48 hours post-dose.

In this context, what does pseudo-irreversible mean? Since it goes on to say the binding had dissipated within 48 hours, it seems to mean persistent or long-lived. Is that correct or does it have a more specific meaning in biology?


texts: Why does the scalp hair become grey first?

texts: I understand that when the hair follicles produce less melanin or stop producing melanin altogether, hair becomes grey. But it seems like it is the scalp hair that becomes grey first. If follicles are producing less and less melanin, shouldn't the hair everywhere become gradually grey? Why is it that the scalp hair greys first?


texts:
Could you please help me identify this caterpillar (Amazon rainforest, Peru)?
Is it a species of Megalopygidae???


texts: What is this thorny plant with cute leaves?

texts:
I found this thorny plant with cute leaves growing in my garden in India,

I took a risk by plucking it to get photos of the front & back side of the leaves.

Front side of the leaf:

Back side of leaf:

Full plant:

Any Idea what this plant is?


texts: We found this skull on a beach in southwestern Sweden, and are curious as to what kind of animal it was.


texts:
What drugs will make rats less cautious/sensible and/or more hungry so they'll go to my snap traps more?

What dosage and how do I deliver it to the rats?

Background info:

The rats trapped in my crawl space I imagine have limited food, if any.
The snap traps are well coated with peanut butter scent but the process is very slow -- one by one.

They have rat mites (blood-sucking parasitic barely-visible mites) and I want them out ASAP.
It's been several months because:

They reproduced down there.
One of the vents got broke open again so a second batch got in. I don't know how many. 25 rats have been trapped so far (2 today and I hear more).

I've checked the house so well. Sealed up with caulk and expanding foam every hole. Checked the roof. Sealed wire mesh on all the plumbing stacks and exhaust vents on the sides of the house.
There's really nothing else. I'm positive it was the broken foundation vent that let the new ones in. But now that everything is sealed securely and won't be broken open again, I think it's only a matter of removing the existing rats.

I don't want to poison them because then they'd die inaccessibly and their mites would swarm the house. They have to die in the traps that I check several times a day, so they can be removed before the mites spread.


texts: How does a single-stranded RNA bind to a double-stranded DNA to form a "triplex structure"?

texts:
If you have a single-stranded RNA that is complementary to a double-stranded DNA, how do they interact to form what my prof. calls a "triplex structure"?

e.g.

    UGCUGAUAGCUACG
ACGTACGACTA
TGCATGCTGAT

I don't understand how the DNA can form 2 bonds there?


texts:
Agglutination test

  Latex agglutination using bound antigens : by coating soluble (non - particulate ) antigens on to microscopic latex spheres, their reaction with a particular antibody can be visualized.

  Haemagglutination : red blood cells can be used as agglutinating particles.

What are non-particulate antigens ? Why are they used instead of particulate ones ?

How are red blood cells used as agglutinating particles ?


texts: Bug identification - Beetle, grasshopper, moth-like and it also flies

texts: Could anyone please help me identify this creature? It can fly and seems to like crawling as well. It has mandibles that are beetle-like.  Approximately 3cm/2inch. Location: KwaZulu Natal, South Africa


texts: why do our eyes not go red in response to body temperature?

texts:
I know that blood flow increases/decreases in response to temperature change, which is why (lighter-skinned) people go red when they are hot.

I know that the eye contains lots of blood vessels.

Why do our eyes not turn red when we are hot?


texts: Can siRNA induce DNA methylation in mammalian cells?

texts:
Some years ago Hiroaki Kawasaki and  Kazunari Taira published an article called "Induction of DNA methylation and gene silencing by short interfering RNAs in human cells" in Nature:

  In plants, dsRNAs targeted to CpG islands within a promoter can also
  induce RNA-directed DNA methylation3, 4, 5, 6, 7, 8; however, it
  remains unclear whether gene silencing mediated by DNA methylation can
  be induced by dsRNAs in mammalian cells. Here, we demonstrate that
  short interfering RNAs (siRNAs; 21–25-nucleotide RNA molecules) induce
  DNA methylation and histone H3 methylation in human cells.

This paper seemed to show that siRNA can also induce long-term silencing of genes by DNA methylation in mammalian cells, which hasn't previously been observed. Unfortunately, the paper was retracted later, calling the results into question.

I found the paper very exciting at the time, as it suggested the possibility to perform gene therapy, to silence specficic genes, just by using RNA interference.

What is the current scientific consensus here, is there any convincing evidence that siRNA-induced DNA methylation is possible in mammalian cells? Was anyone able to replicate the results from Kawasaki and Taira?


texts:
Place: South India,

Metropolitan, Year: 2017; Night Time.

Size: 1-2 cm (Very Tiny)


texts: Has the age at which menopause occurs changed throughout history?

texts:
I was reading recently that the age of menarche has decreased in the last 150 years, and was wondering if the age of menopause in humans has also changed recently?

Would there be selective pressure for it to increase currently, given that the average age of women having their first child is increasing in the West anyway?


texts: What is preliminary work in a biological investigation?

texts:
Here is an example of preliminary work that confuses me (from an A level Biology exam question). Please help me by providing an explanation of preliminary work in the generic sense, then use the example below.

  A company is in the process of developing a new stain-removing washing liquid.
  They want to include a protease enzyme to digest the proteins that are responsible for some stains on clothes. Plan an investigation to discover the optimum concentration of protease to use in this new stain-removing washing liquid.'

Here are the answers suggested as the preliminary work:

  see if proposed method will work / will provide
  measurable results
  to check for suitable conditions for digestion
  e.g. temperature, pH
  select timescale (for measuring stain digestion)
  idea of selecting a range of protease concentrations
  check if the type of {protein / stain} is affected
  select suitable dependent variable for measuring {digestion / removal / eq} of the {stain / protein/ eq }

Now, in my process of understanding what preliminary work is, I want to
question is there any other preliminary work that could be done on this investigation? Seems like there is a lot more to prepare for such an investigation. For example, at first sight, I suggested that secondary research needs to be carried out in order to identify the mean amount of stain and its distribution around that mean. Then that will be the suitable substrate concentration to be used. I also mentioned researching the type of proteases that the company wanted to use, alongside carrying out the preparation of the range of concentrations of enzymes that need to be used.


texts: What is the point of inter-species specific quorum-sensing?

texts: So apparently, according to this TED video, there is a kind of quorum sensing involving a universal, inter-species specific molecule that all bacteria secrete. Is there any evidence of bacteria being able to examine levels of other species-specific bacteria, rather than just any bacteria that can secrete that universal peptide? It just seems like its not enough to generally survey the amount of ANY bacteria in relation to that of your own species.


texts: How do people digest fat after gall bladder removal surgery?

texts:
How do people digest fat after gallbladder removal surgery?

How can they tolerate a high fat diet?


texts: Through what mechanism does cholesterol act as a stabilizing agent and why does it depend on temperature?

texts: As I understand it, at higher temperatures cholesterol has a tendency to make the membrane less fluid, and at lower temperatures it makes it more solid. My question is, what mechanisms causes this? At lower temperatures does cholesterol interfere with the electrostatic interactions between the tails, thus decreasing their ability to congregate and form more solid structures and at higher temperatures does it provide more places for those interactions to occur, thus decreasing fluidity? If so, why is that temperature dependent? In short, through what mechanism does cholesterol act as a stabilizing agent and why does it depend on temperature?


texts: What is the function of the human eye white?

texts: If you have a look at the eyes of most animals, you never see the white part unless the eyes are averted. In contrast, humans always have the whites visible because the iris is quite small. The only explanation I found so far is that the evolution made it this way because we are very social animals and we express a lot by eyes movements. I wonder if there is any other explanation?


texts: Why can myopic eyes focus on nearby objects, but not on distant ones?

texts:
In myopic eyes, far away objects get blurry. I understand that myopia means that the focus of the lenses concentrates light at a point in front of the retina, thus by the point the light rays reach my retina they've already spread apart so they aren't coalescing on the same point as they ought to.

My question is, why is it that this deficiency only apparently manifests itself when things are far away?  Why is it that the focusing of light in front of the retina doesn't cause the same blurry vision up-close as it does far-away?


texts: Can paralogous genes be under negative selection?

texts: I have just aligned 9 paralogous genes from human, uploaded them into MEGA and calculated  negative selection. Can there be negative selection acting in between paralogous genes? Or how should I interpret this result?


texts: Length differences between physically interacting proteins

texts: What can be said on the length differences between interacting proteins? Are they usually of similar sequence lengths or not at all?


texts: Where exactly is 'Colloid' with regards to synthesis of thyroid hormones?

texts: I've researched colloid and it seems to be a substance of microfibres and thin films in which thyroid hormones may be synthesised, but I was wondering where this exactly is... I think it could be in the inter membrane space but I have no evidence of that, or is it just surrounding all cells?


texts:
What is the difference between replication and to divide? My A level bio book says that it takes 20 min for E.coli to divide and in next page it's written that E.coli completes replication within 38min.

Moreover, there is a diagram (shown below) which contradicts as what I thought.

Please explain the difference between replication and division.


texts: Can the respiratory quotient be calculated from a formula or must it be measured directly?

texts:
I found the following question on the Respiratory quotient:

  A normal human diet has a  Respiratory quotient (RQ) of approximately 0.85. Given that pure oxidation of fatty acids has a Respiratory quotient (RQ) of 0.7 and pure oxidation of carbohydrates has Respiratory quotient (RQ) of 1, can one determine the fraction between the amount of oxygen used for aerobic respiration of the fat and the amount used for aerobic respiration of the carbohydrates?

My solution:

$$\text{glucose} + \ce{O_2} + \text{fat} + x \, \ce{O_2 \rightarrow} \ce{CO_2} + 0.7x \, \ce{CO_2} \, + \ce{H2O}$$

Note that I haven't balanced the equation excepted for $\ce{O_2}$ and $\ce{CO_2}$ where I added coefficients based on the given RQ. This equation gives $$\text{RC}_{total}=\frac{1+0.7x}{1+x} = 0.85$$

Hence $1+0.7x=0.85(1+x)$, which gives $x=1$, so the amount of oxygen used for Aerobic respiration of the fat and the amount used for Aerobic respiration of the carbohydrates is equal.

Is this correct?


texts: Best data repository to publish a large 'plotly' table containing all annotations on a transcriptome?

texts:
I want to publish a transcriptome paper, along with interactive materials enabling readers to peruse the data behind the discussion. The R package 'plotly' enables rendering online-publishable tables that can be filtered & searched for specific entries.

I would like to publish such a table as supplementary to a paper (e.g. preprint version) however usually data repositories allow for uploading files and text. I intend to deposit the first version of my main manuscript to Bioarxiv, where they primarily publish .pdf files.

Would anyone here know an official data repository with a format such that would enable publishing online an interactive table?

A good example of such a table is given here.

Disclaimer: I have also asked this question at SE BioInformatics. Like me, they are unsure which would be the best fitting SE Community.


texts: Is the human eye supposed to see the lense effect?

texts:
Just as the GoPro cameras, we need lenses to be able to focus. Nevertheless, we can see the "fisheye effect" on the shots taken by GoPros. I am talking about this:

Is it possible to notice the "fish eye effect"? Or does the brain somehow eliminate this distortion?

[EDIT:]
My insufficient knowledge of optics tells me that, as we have lenses in our eyes, we should see the worlds through a thicker layer of mass in the middle of our field of vision, and through a thinner layer of mass on the margins of our field of vision. We know that our vision is reversed when it enters the eye. Is it inflated in the middle as well?

Is there any "distortion" in the proportions of different parts of the image (that is filtered-out at brain), or the does the image formed in retina have the proportions of different parts same as the actual scene?


texts: Why some traits are more desirable in the sexual selection?

texts: For example, why do peacock females choose males with the biggest tail? If there is no advantage in such tail.


texts: Are there plants that produce (audible) sound?

texts:
Are there any plants that are at least able to produce some sort of sound? Actively, I mean - depleting energy reserves to produce an audible output, preferably with no experimental amplification. Ultra- or infrasound is also ok.

Edit: I guess a different way of asking this is, "Are there any plant parts whose function is to produce sound?"


texts:
What is the cause of high blood pressure? or, Which foods can cause high blood pressure?
Is it just sodium, or sodium chloride? I'm confused because sodium chloride should ionise in the aqueous medium of the stomach.

It'd be great if someone could share the working details/mechanism of the same. Thanks in advance!


texts: Is this answer about the limiting factor correct?

texts: The graph shows the result of adding both phosphorus and nitrogen to different algae populations. I have a hard time figuring out why the correct answer is C, I thought that  groups 4 and 5 would have nitrogen as a limiting factor because adding it increases their growth. Help me please.


texts: What is the difference between a signal peptide and a transit peptide?

texts: From what I know, the two names are used interchangeably and I haven't found any resource which says otherwise either. Is there at all any difference, is there a transit peptide that is not a signal peptide or vice versa?


texts: Do any organisms recycle their own waste internally?

texts: I thought of this question yesterday and it turns out it's surprisingly hard to Google.


texts: To have a drug travel to a specific place in the body can you just coat the drug in extracellular signals recognized by target cells?

texts: In a lecture of mine the professor was talking about the issue faced in regards to drug therapy when it comes to targeting lung cells in cystic fibrosis. It was said that if unless the drug gets targeted just for the lungs it could simply travel randomly throughout the body and thus not effectively treat the disease. My question is if cells internalize extracellular signals and travel/respond accordingly why can we simply not coat a drug for cystic fibrosis in extracellular signals that specifically bind to lung cell surface receptors?


texts: There is evidence for the uptake of toxic substances like prions from the cell bodies of neurons via endocytosis.  There is also evidence for prion deposition in white matter.  But I haven't been able to find a discussion of whether or not endocytosis is possible from axons.  Does anybody know if this is possible?


texts: Are cells really the basic unit of all life?

texts:
Please see comments as to the appropriateness of this question on biology SE.

All known life on Earth is made up of cells. It is thus safe to say that all known life is characterized by the presence of cells. But is having cells as a basic unit a requirement for life?

I'm thus asking if life is currently existent and/or possible without biomembranes, and to what degree cells actually matter in our present understanding of life.

An all-encompassing, comprehensive and cited answer would be very much appreciated.


texts: How do we predict the lifespan of dinosaurs?

texts:
Of course, they are fossils now. I found a link here which states that herbivors lived far longer than carnivores. The example being a T-Rex being "old" at 29, and a herbivorous Bothriospondylus having not reached half it's adult size at 43 years old.

But, is there any evidence that can indicate their life spans, or life spans of at least one kind of the dinosaurs?

An additional brief question is are their lifespans comparable with modern day descendants?


texts: Physiology of tricuspid and bicuspid(mitral) valves

texts:
The tricuspid and bicuspid valves are atrioventricular valves. Both are valves that prevent backflow of blood pumped from the atria to the ventricles. However, the former has 3 "flaps" while the latter has 2.

Despite searching the internet, I could not find a biological explanation for this difference.

Might this be just a relic of evolution or some sort?


texts:
My understanding of r- and k-selectors does not go deeper than the wikipedia article. I understand k-selectors to be creatures that put tendentially more effort and energy into rearing their offspring, but produce tendentially less offspring.

With cannibalism I don't mean eating their own on rare occasions, like after a plane crash in the Andes, but exibiting cannibalism outside of extreme situations.

My gut feeling tells me that expanding much energy into raising an offspring and then eating her does not make much sense, but the world is big, there's lots of different species of animals and most of them are weird once look closely enough.

A good answer explains why one species is a rather to be seen as a k-selector, and in what contexts the cannibalism happens. Since we are talking about a sliding scale of behaviours, the question might as well be read as: What cannibal is the strongest k-selector?


texts: Exact average molecular weight of a dsDNA basepair

texts:
I am trying to calculate the exact weight of a given dsDNA.
On the Internet and the literature, different values for the av. molecular weight of one basepair are given :

660 g/mol (probably wrong),
other sources say 617.96 g/mol
Thermofisher gives 607.4 g/mol
(https://www.thermofisher.com/de/de/home/references/ambion-tech-support/rna-tools-and-calculators/dna-and-rna-molecular-weights-and-conversions.html)

I tried to calculate the average weight using following molecular weights:

molecule
.
weight

2'-Deoxyadenosin- 5'-monophosphate
dAMP
331,22 g/mol

2'-Deoxycytidin- 5'-monophosphate
dCMP
307,197 g/mol

2'-Deoxyguanosine 5'-monophosphate
dGMP
347.2212 g/mol

2'-Deoxythymidine-5'-monophosphate
dTMP
321.2005 g/mol

water
H2O
18,01528 g/mol

adding the matching nucleoside monophosphates together and subtracting one water for each peptide-bond condensation (one on the sense; one on the antisense side);
I get following formula for the average dsDNA basepair weight:
$$
avg.BP.weight = \frac {(dAMP+dTMP-\ce{2H2O})+(dGMP+dCMP-\ce{2H2O})}  {2}
$$
resulting in :
$$
\frac {(331,22+321.2005-36,03056)+(347.2212+307,197 -36,03056)}  {2} = 617.3892 \frac{g}{mol}
$$
which is very close but still 0.57081 short off the "best" literature value.
What am I missing?; Im trying to get this calculation as exact as possible.
Maybe i didn't consider some hydrogen or protons in bonds?
Thank you in advance!


texts: Do distinctions between dry, tickly and chesty coughs have any medical basis?

texts:
Background

At least in Britain you normally come across distinct kinds of cough medicine "chesty", "dry" and "tickly".

Questions

Are "chesty", "dry" and "tickly" coughs always due to microoganisms?
For the types of cough that are infectious, are differences due to different species of micro-organism or the same micro-organism at different stages of its development?
Do the alternative treatments (e.g. levomenthol, squill, liquorice for chesty vs. glycerol for dry/tickly) merely deal with symptoms or do they actually help fight the infection?

Related

A related question is: What is the cause of dry cough?


texts: Why don't self pollinated crops show inbreeding depression?

texts: Being continuously self pollinated means the fusion of same/similar genes from time to time, then why don't they show such a decrease in productivity?


texts: What is the most common way of administering loop diuretics and what is their time course of action?

texts: I am reviewing some material on loop diuretics, and I am curious to know how these drugs are administered. Also, I am interested in knowing their time course of action once they are administered into the body.


texts: Can the third sex be categorized as Male or Female?

texts:
Hijra are people who have a penis (not sure if sexually active) but look much like a female (perhaps for some feminine biological property). Wikipedia says they are "physiological males who have feminine gender identity"

Also, I just came to know there are some more types of third gender people.

Now, is there really any BIOLOGICAL third gender which cannot be categorized as male or female? Or its always possible to categorize them to male or female?


texts: How does the MET gene work and what happens when the promoter region gets mutated?

texts:
I am doing research on inherited risk of Autism Spectrum Disorders(ASD) due to common Copy Number Variants(CNVs) One of the mutations is the 'CC' variant of Rs1858830 in the promoter region of the MET gene. (http://www.snpedia.com/index.php/Rs1858830)

After digging a bit deeper I found that hepatocyte growth factor is a pretty ubiquitous compound in the body and it's necessary for growth/repair of many tissues, namely the liver and digestive tract. I am trying to separate the direct causal effect of the mutation itself from the effects it has on other tissue which may themselves have an effect on ASD risk.

My question comes from a study which measured reduced serum HGF levels in autistic children with this mutation. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3694825/)

I am confused about the implied causal effect of the 'CC' variant on HGF levels even though it is merely the ligand for the MET gene? Please help me understand where in the gene signalling process does HGF come in, what does it do, what proteins are transcribed by the MET gene, and how this mutation effects the transcription of these proteins.


texts:
I read in an ecology text book ("Ecology: Concepts and Applications" (7th edition) by Manuel Molles) that trees in tropical forests can be sustained despite the poor soil is because they extract nutrients from epiphyte mats. Trees send roots from trunks and branches to get nutrients from epiphyte mats that are located high up in the canopy. I would like to visualize these roots. Are there any pictures available (conveniently in the Internet) showing these roots?

Or are these roots usually located beneath epiphyte mats (e.g., very short) and cannot be seen unless we remove epiphyte mats?


texts:
I’m having trouble grasping why small polar molecules can cross the hydrophobic region of the membrane and not ions. Won’t the polar molecules be attracted to the watery extracellular medium and not be inclined to move through the hydrophobic region? (This is my reasoning for why ions won’t go through.)

Also, why do lipid-soluble particles go through the membrane? I understand they have an affinity for the hydrophobic region, but won’t they want to stay there, sandwiched between the two watery layers? Isn’t that the point of the orientation of the bilayer? Why would the lipid-soluble particles move from the hydrophobic region into the watery interior of the cell? Furthermore, why are lipid molecules not repelled by the hydrophilic heads on the exterior of the membrane?


texts: Given that brain waves are characterised as such by virtue of the wave-like properties of 'electrical activity' in the brain, what is the speed of such waves; and how does it differ from neural conduction rates in peripheral nerves ordinarily in the range ~50 cm/sec.  (Oddly I have had difficulty locating an answer to this question elsewhere).


texts: Do all IgG autoantibodies lead to autoimmune diseases?

texts: If there is a presence of autoantibody in our blood, does that mean that we are going to have an autoimmune disease? Are there some autoantibodies which don't cause tissue and organ damage?


texts: Why does GLUT2 (With a high Km), bind less glucose at a lower glucose concentration (below Km)?

texts:
A text I am reading says

"GLUT2 is a low-affinity transporter in hepatocytes and pancreatic cells.
After a meal, blood travels through the hepatic portal vein and GLUT 2 captures excess glucose for storage.

When concentration drops below Km, much of the remainder bypasses the liver and enters circulation. The Km of GLUT2 is quite high so  the liver will pick up glucose in proportion to its concentration in the blood".

I know Km is a measure indirectly of binding affinity.

Rate also is based on concentration so at a higher concentration the rate is higher.

But the passage seems to be saying that at low Km, most of the glucose will not be transported, while at high glucose concentrations, more will be transported.

But i thought Km was a constant so I am confused.


texts:
A friend found this bug, what is it?

Diamond Bar-ish, California.


texts:
I saw this article http://www.ncbi.nlm.nih.gov/pubmed/16710314 and it mentioned pA(2) values and I had no idea what they were. What are they? What do they mean?

If possible it'd be just dandy if you could cite some journal articles/books/other reliable sources for me to dig up.


texts: Where might I find a list of all recorded instincts by species?

texts:
Where might I find a list of all recorded instincts (possibly with all other attributes) by species?

Thanks,
Chenz


texts: Is glutamate always involved in the deamination and amination of the other amino acids?

texts:
For example, are there pathways for the deamination of phenylalanine that simply produce ammonia or pathways for it to be synthesized from phenylpyruvate with ammonia being utilized to form the amine group?

Preferably, I want to know how it is with human metabolism mainly.


texts:
In Stolerman & Olufsen (2001) I read the sentence:

After drug-appropriate responding with the training mixtures reached
85%, generalisation to ethanol was examined in extinction tests.

Here is the entire section from the article on the subject of extinction testing:

Extinction test procedure
Effects of test drugs were determined in brief extinction tests of 3 > min duration that took place twice weekly, with normal training sessions continuing on the interven- ing days. Initially, rats were tested once with vehicle and once with the training mixture; they all reached a cri- terion of at least 80% correct responding and they were all used in subsequent experiments. The effects of saline, the single drugs used for training and the training drug mixture were determined in 3-min extinction tests. The different drug treatments were given in random order. Prior to each test, two injections were always given (via the appropriate routes) to equate handling.

What is an extinction test?


texts: Probability of number of boys and girls being born on a single day

texts:
I am new to genetics, I have the following question at hand :

If four babies are born on a single day, what are the chances that
$A>$ Number of boys and girls will be equal.
$B>$ All $4$ will be girls.
$C>$ At least one baby will be  a girl.
$D>$ Which combination of boys and girls is most likely?

My solution:
Let $X$ be the number of boys .
$X$ follows $Binomial (4,{1\over 2})$ , since the probability of a child being a boy is half.
So the answers are
$A>{3\over 8}$
$B>{1\over 16}$
$C>{15\over 16}$
$D> $ Equal number of boys and girls.
Is everything right ?


texts: Why does atrazine kill photosynthetic bacteria and not nonphotosynthetic bacteria?

texts:
Atrazine was found to bind to Qb, which is involved in electron transport to create ATP in photosynthetic bacteria.

Why does this herbicide kill photosynthetic bacteria, while having little to no effect in nonphotosynthetic?

Is this possibly just because electron cycling creates energy in photosynthetic, and non-photosynthetic heterotrophs use a different mechanism to create ATP?


texts: can you create an offspring from ancient human's DNA?

texts:
If a DNA from an ancient human, for example the cheddar man, is still intact, can you make an offspring today using that intact DNA?

https://www.theguardian.com/science/2018/feb/07/first-modern-britons-dark-black-skin-cheddar-man-dna-analysis-reveals


texts: Improved Vascular Stiffness due to Protein

texts:
I found this study that seems to claim that whey protein is better for your vascular health than casein protein:
https://www.essentialnutrition.com.br/media/artigos/hiwhey/1.pdf
Sure, it seems to be funded by an organization that represents the dairy industry, but I reckon that's why it focuses entirely upon milk protein. I wondered if a similar study has been done on other types of protein, and after a while, I found a quote in this article that claims that plant protein is superior to meat protein for vascular health:
https://www.sciencedaily.com/releases/2015/08/150827083651.htm
Do we know why this is? I know meats and milk have a complete amino acid profile while plants do not. So, why does plant protein do a better job with vascular health than meats? I mean, meats contain all the amino acids that plants provide.
Which books/articles should I read to understand how different proteins and amino acids impact vascular health?


texts:
See paper for distribution of PS-I and PS-II within grana

As explained in the above paper, the PS-I complex is primarily located within non-appressed thylakoid region and stroma lamella, while PS-II in the appressed regions. Now since non-cyclic electron transfer (non-cyclic photophosphorylation) requires both the photosystems, wouldn't their distribution within grana far from one another hamper their ability to carry out non-cyclic electron transport. Although there are mobile untis to account for the electron transport between marginal PS-I and the PS-II immediately below, but the electron transport to the PS-II units deep in the granal core would still be unaccounted for.


texts: Do The Traces Genetic Diseases Remain in families?

texts: I know that there are certain diseases that are predominant on genes. But, is there any sort of surety that if parents are suffering from a disorder then their offspring has to suffer from the same. Like my dad is schizophrenic so will I become the victim of the same mental disorder?


texts: Help me find out what this bird is (description, no picture)

texts:
A while ago I read about this bird(s) whose species status was not confirmed. This was because they had a very large distribution and birds in adjacent population could breed with each other but birds at each end of the distribution (western Europe and South Asia I think) couldn't. I am pretty sure that they were some kind of gull and from Europe to Asia their wings got lighter, from black to grey. I think I might have read about them in a Richard Dawkins book.

Does anyone know the species I'm talking about?


texts: How does a diploid sporophyte form in non-recurrent apomixis?

texts:
I came across this definition of non-recurrent apomixis which occurs in angiosperms-

In non-recurrent apomixis, both the egg-cell and embryo are haploid and embryo is developed directly from an egg-cell without fertilization.

If this is the case, how does a diploid sporophyte develop from the haploid embryo? Are there any examples of the same?
I think most likely it would be by free nuclear divisions, that seems like the best bet, but I'm not sure if that's how it occurs.


texts: What flower is this grown in Southern China

texts: It is grown in Tropical Southern China. It is not wild.


texts: Is it possible to label a DNA molecule using a radioactive sulphur?

texts: The radioactive labelling of the DNA molecule is possible using radioactive phosphorus and tritium atom. But is it any how possible to label the DNA  molecule using a radioactive sulphur atom?


texts: Why is the human body hair not uniformly colored?

texts: Most of my body hair is black however my lip hair is light brown/blonde the rest of my beard region is black. Since hair color is genetic what causes this?


texts:
It has since cocooned I think but it was a weird circumstance. I kept adding leaves for it to eat, and it decided it was done, and cocooned under a wilted leaf.  I'm wondering if anyone can ID the species, and the following: I think it is a real cocoon, as there is no dead or rot smell.

But the cocoon was under the wilted leaf, and is now quite firmly attached. In the pics below, I've turned the leaf and cocoon over. Does the cocoon know "up"? And does it know it before or after making the cocoon? If it was stuck on its "up and out" direction, can turing it over be harmful? I.e. I turned it over so now it's trying to emerge towards the ground, can it figure out how to find 'up'?

Locale: Southwestern United States
Found in: found it in a moist garden bed (tomatoes, radishes, peppermint, basil) eating radish leaves
Description: About 2 inches long, 1/2 inch long hairy, black/grey hairs, body is black/grey with yellow striped markings

Cocooning position: wilted leaf / \, stick |, cocoon (), ...

 /|\
/()|\

Summary: It made the cocoon with the leaf on top of it, and it would never make it out in that case, so I turned it over. Is that okay? Can we still see the winged form come out? Like I said, it doesn't smell dead... in fact smells better than when the caterpillar was pooping everywhere.

Aside, this is the only tag I could find that might fit. Please feel free to edit tags to get this answered. TY

Caterpillar

Cocoon after being turned over, you can see it's kind of wrapped in the leaf