texts: How greater magnitude implies greater frequency of action potential?

texts:
Greater the magnitude of receptor potential, greater is the rate of discharge of action potentials in the nerve fibre.1

Now consider a case where stimulus ( strength ) is large , so there is more accumulation of positive charges near the spike generator region, this would then form action potential , this action potential should then travel in both directions just like at initial segment , where SD spike clears the existing EPSPs, so if I apply same logic here then antidromic Action potential should clear those generator potentials. If I am right then how is more stimulus causing more frequent action potentials?

Case2: If we take the scenario where there is no antidromic conduction of action potential ( for some unknown reasons) then more and more generator potentials are coming at spike generator region(1st node of ranvier) then also how it is causing more frequent action potential generation , if we consider that fact refractory period is constant for all action potentials( in a particular neuron)?


texts: Finding specific genotype occurrences given allele frequency

texts:
So let's say I have a tetraploid species and I have 4 possible alleles for a particular locus. I have found that I can have 35 total possible genotypes and I know the allele frequencies for each of the 4 alleles, that I will randomly set as $$F_a = 0.2, F_b = 0.3, F_c = 0.4, F_d=0.1$$ for the sake of the example.

However, I am having a hard time wrapping my mind around how to calculate the number of occurrences of a particular genotype, $abc$, in a population of 1000 people.

I understand the allele frequencies, for instance, in the population of 1000 people, given all 1000 observed genotypes, 40% of them had allele $c$. But these are individual values and I have no information on how likely they are to be linked. (I am supposed to assume HW principle holds, but not sure how this helps).

How do I calculate the number of occurrences of the genotype $abc$ in the population?


texts:
On the 3rd diagram (from left), the one with net charge = -1 ,

Why did it lose the H to OH- from the CH2CO2H from the neutral form ?

I was told that while moving to the right , the OH- will take H+ electrons meaning it should take H+ from NH3 .. ?

Is there any reason why they took the H from CH2CO2H ?

Any help would be appreciated!


texts:
I know that in G1, the number of chromosomes is 23 pairs, so 46.

I assumed there were 46 chromatids too.

Why is the number of chromatids in G1 actually 0, not 46?

Thanks.


texts:
Pure-breeding tall and pure-breeding short pea plants in the P generation were crossed as shown below. Based on the diagram below, one can assume that

a)short plant height is the dominant trait.
b)the F₂ generation will all be tall in height.
c)the alleles for plant height do not segregate during meiosis.
d)tall plant height is the dominant trait.

My answer: The answer is D becasue tall plant is the dominant trait because  A dominant trait is an inherited characteristic that appears in an offspring if it is contributed from a parent through a dominant allele


texts: Evolution of parasite into ideal parasite

texts:
An ideal parasite is a parasite which thrives within a host without harming it (according to my NCERT textbook).

Then, quite obviously, why hasn't that happened yet? I mean, natural selection can lead to such a species, which is beneficial to us and also, not at all detrimental to the parasite.


texts: How does sGP of Ebola virus help it to evade host humoral immunity?

texts: During Ebola infection, the viruses secret a lot of sGP. What's its function? Since anti GP antibodies are effective at inhibiting Ebola infection, wouldn't sGP stimulate host immune system to produce more anti GP antibodies? Why does Ebola virus expose its weakness deliberately?


texts: What are these lentil like eggs? (Utah, United States)

texts:
I've found these (what appear to be eggs) attached to an apple tree in central Utah USA.

The eggs are less than 1/2cm in length, have a waxy appearance and are attached to the branch at one end. Visually and tactilely they are quite similar to lentils.

I thought they were Box Elder bug eggs, but after a google image search I am convinced that is not what they are. What are they?


texts: Distance matrix with different length sequences

texts: In a project we're doing (in python), we want to create a distance matrix for a phylogenetic tree with multiple, different length sequences. However, what we've seen so far (AlignIO in biopython, etc.) requires the sequences' length to be equal. Is there any pythonic way to get the matrix with sequences of different length? Or any other indirect way that would get us to the same result?


texts: Tracking of oxygen molecules in glucose oxidation

texts:
For this reaction, found in typical biochemistry textbook:

$C_6H_{12}O_6 + 6O_2 \to 6CO_2 + 6H_2O$

I am interested in where do the oxygen atoms of $6O_2$ go. I think they go to $6H_2O$, but this is not sufficient for balance. So Does oxygen atom from $6CO_2$ also get into the carbon dioxide. Experimentally these can be confirmed by iostope labeling experiments. Reference to any such experiments will be appreciated.

I am interested in this question because the central metabolism can be understood as a electron transfer process where glucose is donor and oxygen is acceptor. We need to calculate, effectively how many electrons glucose transfers to oxygen in case of full oxidation.


texts:
I was wondering if I d want to analyze something related to my current health based on my saliva. What could it be?

I mean e.g. by putting a thermometer in your mouth you can know your body temperature and know whether your immune system is eventually fighting some disease. But as you already have that apparatus in your mouth I think it would be usefull to prelevate some saliva (hit two birds withone stone) or other stuff in order to eventually easily investigate ones health.


texts: Are the arrows in this diagram of ATP synthase correct?

texts:
I have a question about this image below.
Do you think that the pink arrow is actually going in the right direction?

I would suggest a LTO sequence and not LOT, since it is in the T state that ADP + Pi is converted in ATP.


texts: What do I need to do to make a Reverse colorblind image?

texts: As a 15 year suffering from moderate Protan colorblindness, I've wanted to find any advantages of colorblindness. I discovered there are Reverse colorblind tests, which only colorblind people are able to see the objects. This has fascinated me, and I want to make one of my own. How can I do this? Since I cannot tell the difference between the colors only visible to colorblind people an their normal vision counterparts, how could I do this without buying a pair of Enchroma colorblind glasses so that I may see it with both visions?


texts: What's the difference between Cytoplasmic pool and Granular storage pool?

texts:
What's the difference between Cytoplasmic pool and Granular storage pool when speaking about neurotransmitters and synaptic cleft. I encountered this here:

  Amphetamine’s mechanism of action
  thus depends on the cytoplasmic, newly synthesized, rapidly metabolized pool of dopamine.
  Methylphenidate’s mechanism of action depends
  on the granular storage pool (Brust, 2004)

Reference

Brust, J. C. M. (2004). Neurological aspects of substance abuse. Philadelphia, PA, Elsevier.


texts: Measuring the density of surface antigens

texts: I'm trying to get a sense of the variety of methods used for determining the number of cell surface antigens and receptors. This is notably different from determining the affinity of these surface markers.


texts: Are STOP codons impacted by base insertion or deletion mutation?

texts:
I am learning about base insertion and deletion mutations. An example in my textbook is given below.

GUU CCA CAU AUC.

So if there is an insertion (of guanine):

GUU GCC ACA UAU C_ _ (there will be a detrimental effect on the protein created).

I'm a bit confused about how the stop codon will be read. If we have a new example with a stop codon:

GUU CCA CAU AUC UAG

When the mutation occurs (insertion of guanine) will it become:

1) GUU GCC ACA UAU CUA G

OR

2) GUU GCC ACA UAU C_ _ UAG

If mutation 1) occurs, there would be no stop codon, but mutation 2) looks strange to me. So which is the right one?

Thanks


texts: A number of questions regarding chemotaxis assay using PBMCs

texts:
In our lab we would like to study the chemotaxis of PBMCs towards conditioned medium obtained following treatment of cancer cells with different compounds.
My questions are regarding the method of purification of PBMCs from whole blood:

I have read a number of protocols saying that during the isolation process the buffers used should not contain calcium or magnesium ions, as these can cause the activation of the PBMCs. Is that so? From my knowledge Ca+2 is a second messenger only in TCR signaling. I am not sure reegarding the other cells present, and how magnesium is relevant at all.
Even if I use PBS (without any calcium or magnesium ions) to isolate the PBMCs from blood, in the end I resuspend the isolated PBMCs in medium which does contain these ions. Is there any rationale to use calcium and magnesium-free buffers for the isolation when  the final medium contains these ions anyway?
When I begin the assay, should the PBMCs be activated or not? In other words, do chemokines also activate the PBMCs or are chemotaxis and activation two totally independent processes? How should activation/no activation affect my results?

Thank you in advance.


texts: During inflammation, cytokines and histamine cause vasodilation to increase blood flow to the inflamed area. However, it is also said that vasodilation slows blood flow which facilitates the adhesion and movement of leucocytes through the blood vessels and into extravascular tissue. My question is how does it slow blood flow? To me it would seem that there would be less drag force for a given volume of blood which would increase the speed of flow. There would also be less resistance.


texts: How do T-cells determine which cells they've already inspected?

texts: From what I understand, T-cells are constantly traveling in the body, inspecting cells by looking for antigens. If they're self antigens, then the T-cell doesn't attack, whereas if they're non-self, they attack. My question is how does a T-cell know when it just inspected a cell? Does the T-cell leave something behind on the cell to mark it as checked or does the cell itself present something on its surface to indicate that it has just been checked? If there is no such system, then what prevents the T-cells from being stuck in a loop, and just inspecting the same cell over and over?


texts: What is this plant which looks like "marjoram"?

texts:
Place is India.

We are confused about the identity of this indoor plant. My friend is saying plectranthus, possibly barbatus.
I am saying it is marjoram.

Which is correct name for this plant?


texts:
I searched a lot in the net but don't found a clear answer.
I just want to know if plasma membrane is permeable to sucrose.


texts:
Does every nerve ending send information to the brain separately? Is there a nerve path (I don't know their scientific name) from every nerve ending to the brain; or are they sent to brain from the same paths in the dorsal root ganglion? If not, how can we determine the (almost) exact location of pain in our hand?

I am not very familiar with the biology except the lessons I had taken in the high school. So please try to use daily language explaining this.


texts: How are synaptic vesicles brought to the synapse?

texts:
I'm reading about how synaptobrevin is used to identify synaptic vesicles for tethering near the synaptic cleft. Since neurons have a synapse and dendrites, I'd like to know how exactly  the vesicles get moved from the Golgi to the synapse.

As far as I can tell, they are transported along microtubules by dynamins as opposed to floating freely in the cytosol (correct?). If so how do the dynenins identify synaptic vesicles - would they form a SNARE complex that gets released near the synapse or by some other means?


texts: I am trying to convince a friend that human beings evolved from primates, and he challenged me that advanced mathematical ability couldn't have been the product of mutation and natural selection because this ability wouldn't have conferred any reproductive advantage until the last few hundred years, and the process of mutation and natural selection would have taken much longer than this to produce the extensive genetic basis of advanced mathematical ability. How do we refute this?


texts:
I'm more of a tech than bio kind of guy, but I have read and learned a lot alongside of my girlfriend's education. Which is very interesting!!

Currently I want to investigate : people claiming to feel another persons pain when they are touching them.

I cannot seem to Find any papers about it. I guess I'm using the wrong search terms.
Or does nobody research about it ?


texts: What happens if there is a blood incompatibility during pregnancy?

texts:
There are possible combinations of blood types with the rH factors:

Rh factors are genetically determined. A baby may have the blood type and Rh factor of either parent, or a combination of both parents. Rh factors follow a common pattern of genetic inheritance. The Rh-positive gene is dominant (stronger) and even when paired with an Rh-negative gene, the positive gene takes over.
If a person has the genes + +, the Rh factor in the blood will be positive.
If a person has the genes + -, the Rh factor will also be positive.
If a person has the genes - -, the Rh factor will be negative.

I am aware that an infant receives one gene from the father and one from the mother, but what happens when the mother's Rh factor is negative and the newborn's is positive? What happens if the mother is O and the infant is A or B?
What happens within the placenta and to the maternal blood poles which are connected by open ended arterioles into intervillous spaces? Will the chorionic villi be "demolished" and exchange of materials isn't as possible?


texts: Online Molecular and Cellular Biology Video Lectures?

texts:
I am looking for video lectures to go through to guide my reading in intro molecular and cellular biology. I've had intro bio and I study evolutionary theory, but my molecule- and cell-level knowledge is weak.

I'm finding it impossible to know where to look in a big book like Alberts, or to read Lodish without a guide, so I really need lectures to help me out. I've tried the MIT OCW assignments and a few other similar sites, but I can't seem to find a course that includes lectures. Does anyone know of any? Ideally they'd follow Watson et al. for molecular and Lodish for cellular, but I can find other textbooks too.


texts:
On the physics StackExchange site people are trying to figure how and why these branching structures formed. The two questions can be found here and here. The latter had no cooling fans and was situated in an unventilated cupboard. There are many processes that could explain such structures without them being a bacterial colony, for example by Diffusion-limited-aggregation as explained in my answer here. To me it looks like this could be a bacterial colony. Is there any way to rule this out or say with precision that this is a bacterial colony?

I think some organic material and humidity could latch on to the irregular edges upon which bacteria could then grow in a warm environment.

What ways are there to tell from just a picture if this is a bacterial colony or  not?
What ways are there to tell if this is a bacterial colony or not if you have the structure at hand?
What ways are there to rule out or say that this is some kind of fungus or living thing if you have the structure at hand?

The second pic was taken by Wossname:

  "the equipment is in a temperate climate in a non-aircon area of an
  office building near the external door. In high summer it would get to
  probably 40 Celcius and 85% or more relative humidity in my
  estimation. It's an area of the building that people most definitely
  don't loiter in during July/August. :)"


texts: In the induced fit model for enzyme action, does the enzyme active site change slightly after products form?

texts:
The reason why I am asking is because I am looking at a past paper and they highlight that it does. I have attached it below. Could you explain why this is the case.

I am just looking for a quick overview of why this is the case.


texts:
In Cambridge UK there is this spider:

I know not what species but it is common - I think they look good.

But look at this behavior. What are they doing? I thought malting but do spiders do that? Why would they congregate like this?


texts: Are human males and females more genetically different than members of other species?

texts:
I'm looking at this Ted talk about a Saudi Arabia woman who dared to drive a car in the last few years. This reminds me that until the last century or so, women (all over the world?) enjoyed less rights and might've been pigeonholed into roles predetermined by society. Those roles might've encouraged certain traits, and discouraged others. Those who did not conform might've been punished, like the woman in the talk above received death threats and was jailed.

This sounds to me like selective pressure, did it really exist, and did it have any effect on the genetics/traits of modern women?

This makes me interested in the question - compared to other species, are men and women more genetically different because of selective pressure put on women to conform to male-dominated world for thousands of years before 19th century?


texts:
This year, many acorns in our area (Germany, Schartzwald) fell prematurely, plagued by some kind of warts or gall-nuts which I see for the first time:

Some of the acorns are covered by two or three warts at a time, so that the actual nut itself is practically non-existent.

Judging by the hole present in all the warts, I'm guessing those were houses for some insects or larvae. Unfortunately, warts on acorns available for inspection (those which already fell) are already abandoned by their hosts.

Does anyone know who those guys are and how they look like?


texts: What are the characteristics of a cancerous cell surface membrane?

texts: A notable characteristic of cancer is that it thrives at a high glycolytic rate, and doesn't require much aerobic respiration. I am curious, how does the cell surface membrane composition change so that less oxygen is able to diffuse into cancerous cells? Does the membrane become more rigid? Or how do the fatty acid tails, cholesterol, etc change?


texts: If a venomous snake somehow gets it's own venom in its body, will it be affected by it?

texts:
Here is a hypothetical situation I had been thinking about that sparked my curiosity:

Let's a snake is just slithering around, not being attentive for some odd reason. It happens to pass a mouse, in which it didn't see (this is all just hypothetical), and the mouse freaks out and starts to run. When it does, it trips over the snake's tail, and, not knowing what is happening, the snake snaps back bites the mouse and gives it a good dose of venom. (Now, to my question).If the snake ate the mouse, would it's own venom, now in the mouse, hurt the snake?

(Since they are native to where I live, let's say the snake is a Water Moccasin)


texts: Garden Hose Analogy for Blood Vessel Resistance

texts: I've been trying to reconcile the resistance component of Poisseuille's law with a mental analogy of a garden hose; specifically, I had assumed that the effects of reducing the radius of a blood vessel (of an arteriole in vasoconstriction for instance) would be the same as when you put your thumb over the opening of a hose, causing water to leave at an increased velocity. However, the law instead predicts that a decrease in radius like this would increase resistance, actually decreasing flow by a proportional amount equal to r^4. Why doesn't arteriolar flow actually end up increasing because of the pressure from the arteries, much like its "hose equivalent"? Does the hose analogy even work in this scenario? What am I missing that separates the two scenarios?


texts: Does human digestive system benefit from eating same kind of food consistently?

texts:
Here's the reason why I'm asking: I've heard that it takes some time for pets(cats/dogs) to adjust to a different dry feed, where the new feed has to be mixed with the old one, slowly replacing the old one. I'm wandering if this advice has any truth in it, and if so, does this apply to humans as well?

For example, a cat eats the same kind of food for months at a time, but humans vary their diet  much more dramatically. Are there any benefits to eating the same kind of food over extended period of time? I'm interested in knowing if the digestive system/symbiotic bacteria in the gut adapts to the food, resulting in better digestion/absorption of nutrients.

Thank you for your input!


texts: Are there any examples of sudden leaps in evolution?

texts:
As far as I understand, various abilities like flying, sight, hearing etc. were caused by slow evolution, where those with a greater ability to to these things had better chance of survival. (If this assumption is wrong, then I am happy to delete this question).

Are there, however, any documented examples of by evolutionary leaps being made, over the course of just a few generations? I understand, that some abilities have a tipping point where one gets the ability suddenly, but there is not a lot of physiological change made. An example of this would be the ability to climb a tree, which could suddenly be possible if the body weight is reduced with just a few percent. What my question is about, are sudden changes to the characteristics of a creature.


texts: Species Identification: Red velvety insect, India

texts:
What species is this?

Description:

Location: India
These insects came out just after overnight rain.
They were all over the place.
Their body looks like velvet.

Are these insects poisonous?


texts: Do proteins generally contain phosphorus and sulfur?

texts:
I've heard that proteins generally contain six main elements - carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

I know that proteins are made from amino acids. Amino acids are composed of an amino group, a carboxyl group, a lone hydrogen atom, and a side chain that varies between amino acids. Of the 20 major amino acids, none of them have a side chain that contains phosphorus. Only cysteine and methionine contain sulfur.

So, are sulfur and phosphorus atoms really characteristic in the structure of a protein?


texts: Why does high pH result in the denaturation of DNA?

texts:
In the Southern blot method, for example, a solution of NaOH is used to denature the DNA in the sample.
I find this counterintuitive since I expected that $\text{Na}^+$  cations would neutralize the negative charges of phosphate groups, hence stabilizing the double helix.


texts:
The NCBI talks about "Evolution beyond neo-Darwinism: a new conceptual framework." (source).

What is the difference between the Modern Synthesis and the Extended Synthesis?


texts:
I know this is a very basic question, but it is not too clear to me what is the unit of measure of branch length in phylogenetic trees.
I have come to understand that it is usually expressed in number of substitutions/site/some unit of time.
What is that "some unit of time"? Generations?
Does it depend on what method of tree construction I am using (NJT, MP, ML)?

Thank you for your time.


texts: Is there a scale suitable for continuous tracking and recording of plant weight?

texts:
I want to measure water transpiration and evaporation in a bonsai tree, and measuring the weight of the tree in its pot is my proxy for water usage.  This has worked well with manual measurements, but I want to go to the next level.
I would like to monitor the weight of something continuously (e.g. once a minute) and access the data easily via a phone app.  Is there something like that?
There are numerous options for similar devices if you want to measure ambient temperature and humidity (e.g. https://www.amazon.com/SensorPush-Wireless-Thermometer-Hygrometer-Android/dp/B01AEQ9X9I).
But all my searching for balances with similar functionality have failed.  I've found many lab balances and kitchen scales, and body weight scales.  Only the body weight scales interact with apps on your phone, but they do not record continuously.
If you know of one, or just have better google-fu than me and can suggest a more precise search term, any pointers would be appreciated.


texts:
I've had a giant wasp hanging around outside my window the past few days, so I've resolved to learn more about it. I believe it is a male Cicada Killer, because it displays the following behavior:

During the day, it is extremely localized in a region less than a square meter.
It lands or hovers in the same grassy area all day, and occasionally chases off other wasps that come near it.

First question: Am I correct that this is a male? The females should be off burrowing or catching Cicadas, right? He is quite large (2 inches?), but I don't have a female for comparison in terms of morphology.

Second question: Where does this guy go at night? He leaves before sunset (~5 pm) and shows up again in the morning (~10 am).

Third: If he's around, I should be able to find some female burrows in the area as well, right? Where should I look for these for confirmation?

The question is admittedly a little vague since I am just trying to confirm I understand the behavior I am observing, but I've tried to isolate the specific questions I want answered.

EDIT: Finally got some pictures, only these two came out.


texts: Is my RNA-seq experimental design correct to use it for SNP calling?

texts:
I am a newbie here and would highly appreciate your advice about one particular experimental design.

We have data from RNAseq experiment which was originally designed to assess differential expression. The details of experiment are as follows:

2 modalities of the phenotype

Each phenotype is represented by 4 samples. 1 sample = 60 individuals pooled together at the stage of RNA isolation.

Molecule – polyadenylated mRNA

Sequencing chemistry – Illumina paired-end, read length - 2*100 bp

My question is whether it is correct to use this RNAseq data to call for SNPs? I made previous search and found that most of people calling SNP from RNAseq use 40-1000 samples (= individuals). But they initially designed RNAseq experiment for further GWAS. I see that this analysis cannot be applied to my data (at least because in my case individual flies were pooled without barcoding – 60 flies per a sample). However, can I still call for SNPs and upload the list to database as a list of potential targets for GWAS with, for example, estimation of functional impact upon protein structure? Will they be “true” SNPs, or our experimental design makes even this step invalid?

I found this paper https://www.ncbi.nlm.nih.gov/pubmed/27458203 where people used 2 phenotypes each represented by 2 samples what is almost like our experiment, but still have doubts.


texts: Authority on Microbiological Definitions

texts:
Is there an authority on definitions for molecular microbiology concepts, like an IUPAC book for chemical definitions?

The particular definition I am debating is chromatin. Some say it encompasses DNA, RNA and protein, whilst others say that it contains DNA and only during the mitotic interphase can it transcribe to produce RNA and protein.


texts: Why do men have a greater chance of suffering from hair loss?

texts: If we look around we'll find that men are more likely to suffer from hair loss when compared to women. Is there is any specific reason for this?


texts: where can I find a full list of examples of data types in biology?

texts:
I have no background in biology and I would like to build a collection of the data types in biology. I start searching and reading bout that and found there are 7 data types:

1-Sequences: DNA, RNA, Protein
2-Structures of biological molecules
3-Gene expression profiles
4-Biochemical pathways
5-Chromosomal mapping
6-Phylogenetic data source
7-Single Nucleotide Polymorphisms (SNPs)

and I search for a schema that defines these types and found EDAM ontology http://edamontology.org/pag but it does not help me.
Do you have any idea where I can find a complete list of examples of the data types mentioned? or at least for one of those data types? Any reference will help me.

Thank you


texts: What prevents the human intestine from 'exploding' as a consequence of bacteria growth?

texts:
Usually bacteria grow by dividing and they can do that very fast. So after a couple of hours or days you have many bacteria in your intestines.
And we keep feeding them by eating. In some way you would expect that the growth of bacteria has been so overwhelmed that after a week our intestines would 'explode'.

Of course this doesn't happen, but what factors protects our intestines from bacteria overgrowth?


texts:
I know that difference between different colors of light is difference between their wave length but I don't know what gives beautiful colors (like rainbow colors) to different wave length of observable light?

What makes our eyes to see different wavelengths of light as different colors?

Remark:
I've meet someone which he was color blind, he was not able to see rainbow colors.
So the process that gives color to light must be in our eyes and brain.


texts: Formula for Oxygen Consumption for Atlantic Salmon (Mathematical) - insecurities regarding variable

texts:
The oxygen is calculated in mg per kg per something, so what does $h^{-1}$ stand for? hours maybe?

The formula given below is an estimation of oxygen consumption for Atlantic salmon

  \begin{equation}
        V_{O_{2}} (mg \cdot kg^{-1} \cdot h^{-1}) = 61.6(\pm6.6) BW^{-0.33(\pm0.11)} \cdot 1.03(\pm0.10)^{T} \cdot 1.79(\pm(0.10))^{U}
    \label{eq:salmonoxygenconsumption}
\end{equation}

Here is a link containing the scientific article describing the formula - ScienceDirect


texts: Is there a point in our life when ALL the atoms from our childhood's body get replaced?

texts:
The evolutionary biologist and Oxford professor Richard Dawkins makes on his TED talk the rather interesting suggestion that we human beings, are in nature more similar to a wave than an object. In the sense that we are a persistent structure travelling trough a constant flow of atoms that only transiently form part of our body.
Citing Steve Grand and his book Creation: Life and How to Make It, he argues that the body of a grown up man doesn't preserve any of the atoms that formed his body by the time of his earliest childhood's memories.
Is that fact widely accepted by the scientific community?

I know that this question is a duplicate of Are all body atoms really recycled several times during a life? (or this one), however I want to put the emphasis on the atom constituents of cells, as the accepted answer there doesn't fully answer that question.
Following those answers and the references within, a consensus seems to exist that most of the body is in constant renovation, with the exception of the cells in the cerebral cortex and the inner lens of the eye, whose cells persist trough life. But to what extent cellular metabolism replaces individual constituent molecules and atoms throughout those cell's life? Is that true also for DNA? What about mitochondrial DNA?

Are the processes that repair DNA damage operating only in damaged areas? Or do they constantly "repair" also healthy areas leading to the constant replacement of the atoms that constitute the DNA?

Others argue that tooth enamel does not regenerate or get replaced, been that what allows carbon dating to be accurate to the year of birth plus or minus a few months. However, as my question begins with a philosophical issue, I'm mostly interested in the atom constituents of the cerebral cortex. I am in particular aiming to figure out if we are more precisely described as a brain travelling through time or just a wave in a sea of atoms.


texts: In all histology books, it is stated that all sensory nerve endings (receptors) consist of dendrites that translate physical stimuli from the environment into neural signals. However, several sensory neurons seem to include axons, such as the merkel and olfactory cells shown below. They act as receptors, but feature axons as well. So is it the pictures, or the texts that are incorrect?


texts: How to increase the rate of absorption and assimilation of food?

texts:
i was reading this
and want to know

excerpt from the above linkThus, the time for food to travel from one end to the other probably ranges from about 20 to 30 hours
I believe it's 24 hours for a normal person going for poop every morning, But I was curoius if anybody could increase the rate of absorption making my digestive and defacaeting system better performing.


texts: Pros and cons of amino acid structure vs DNA sequences for evolutionary comparison

texts:
This is an analysis question for a lab on the amino acid differences in beta globin amongst different primates, and using such differences to construct a cladogram and infer evolutionary relationships from it. Any input is greatly appreciated!

Question:
What do you see as the strengths and weaknesses of using amino acid structure of proteins for evolutionary analysis? In your opinion, would it be more useful to use DNA sequences for this type of evolutionary comparison between living and extant species? Why or why not?


texts: Functions of tracrRNA and crRNA in the CRISPR/Cas9 system

texts:
I need some help about Crispr / Cas9.
The CRISPR/Cas9 technic consists (for bacterias) in "cut" bacteriophage's DNA, in order to make it unfunctional.
When the RNA is transcribed (RNA which is complementary to the bacteriophage's DNA), it will be associated with crRNA and tracrRNA to form the sgRNA (single guide RNA).
But I would like to know where crRNA and tracrRNA are from? and what are their function(s)/ goal(s).

Sorry If I made mistakes I'm French.


texts: Is the rate of photosynthesis higher than the rate of respiration?

texts:
In photosynthesis carbon dioxide is used up and oxygen is produced and at the same time plants respire too. So oxygen is used up and carbon dioxide is produced.
Then the net exchange of gases should be zero. If this is so, then why do we say that plants maintain the level of oxygen and carbon dioxide in the atmosphere?

So, is the rate of photosynthesis higher than the rate of respiration in plants in a year(overall)? What is the net exchange of gases annually?


texts:
When we reach for an object, for example, a cup, is the force used to hold it a reflex? Which sensorial information is used to select the force to hold it?
Why I am interested in this question

With the development of robots with dexterity, it is necessary to develop a minimal amount of sensors so they can choose the strength to hold an object. Objects that look heavy and slippery need more force, while objects that are delicate need a lower force. Do we unconsciously use visual information to decide the force to hold an object? Can this be called a reflex?

When we reach for an object and it feels painful to hold it (it is too hot or too sharp) we immediately release it, is that a reflex?

In my search I found mostly results about the grip reflex of newborns. Is it Completely lost in adults?

(a personal reason) recently, I noticed that my grip force calculation is kind of “uncalibrated”. I am dropping cups, tools, my cellphone, more frequently than before. However this is not a problem of grip Force or shaking, I can hold myself on a bar with one hand and I have zero hand shaking on my hands. So, when I consciously choose to hold it, I have force, but when I am not thinking of which force to apply, I drop things. Note: this question is not for self diagnosis, this is just the initial observation that sparked my interest in the question.


texts:
I am supposed to calculate the relative rate of evolution of two sequences (human and sheep) with a chicken serving as the outgroup. The sequences are pretty long, so I will just create a short example since I just want to learn the process (we are expected to use online resources to figure out our homework problems since it is an online class, but I can't find any examples).

Human:   GGATGCGCCT
Sheep:   GGACGCGCCT
Chicken: GGACACGCCT

Can someone show me how to do this? Here is my guess from the limited info I found, but I have little to no confidence that it is correct:

p-distance of human/chicken = 2
p-distance of sheep/chicken = 1
relative rate of evolution = 2/1 = 2

Is this correct? If not, can someone show me how to do it correctly?


texts: Do blood glucose "spikes" contribute to insulin resistance, or is prolonged elevation required?

texts:
There's increasing public discussion about the health risks of chronic insulin resistance* (IR). In many cases there's a focus on high glycemic index foods that "spike" your blood sugar, which implies that a rapid increase in blood glucose is by itself sufficient to contribute to IR.

On the other hand, I've heard the claim that if a person is 1) moderately active, 2) not in caloric surplus, and 3) not already insulin resistant, then they will will quickly clear excess blood glucose by replenishing glycogen or through general energy expenditure. This is claimed to have no effect on IR, even though the individual was temporarily exposed to elevated glucose / insulin.

This leads me to two questions:

1) Is it true that high blood glucose is normalized substantially more rapidly in people who have depleted their glycogen, or who have higher energy needs?

2) Does repeated exposure to high levels of blood glucose contribute to IR by itself, or are high and prolonged levels of blood glucose required?

This has public health implications -- If the "spikes" theory is inaccurate, then glycemic index may not be very important to sufficiently active people**, and low glycemic index meals may not be as helpful as expected for people at risk of developing IR if total glucose exposure is high.

*"chronic insulin resistance" would exclude gestational diabetes and the reversible insulin resistance seen on ketogenic diets.

**For this discussion, let's ignore effects of blood sugar swings on hunger, mood, behavior, etc, since my interest is in the specific physiological triggers for IR.


texts: Finding for evolution, comparing past flower numbers with present

texts:
In a hypothetical species of butterfly, wing spots are controlled by a single locus where BB individuals have blue spots, YY individuals have yellow spots, and BY individuals have green spots. Ten years ago, a previous collector randomly collected 1000 butterflies and reported finding 90 blues, 420 greens, and 490 yellows. You collect 40 blues, 320 greens, and 640 yellows. Has there been evolution in this population? If yes, is natural selection involved?

I have had many attempts at this question I calculated the p and q frequency for each using HW model.

For 10 years ago: 90+90+420/2000=0.3   BB
490+490+420/2000=0.7 YY

For now : 40+40+320/2000=0.2 BB
640+640+320/2000= 0.8YY

But I dont think I can know if evolution happened and natural selection from this (because Y allele in yellow for instance includes heterozygotes as well).

What do I do? Do I calculate the expected number of each and put it in Chi square test but how would I get natural selection from that? Please help


texts: What's the therapeutic index of Pethidine (Meperidine in the US)?

texts:
What's the therapeutic index $\left(\frac{LD_{50}}{ED_{50}}\right)$ of Pethidine (Meperidine in the US) via the intravenous route for humans or whatever species you can find? The therapeutic window $\left(\frac{TD_{50}}{ED_{50}}\right)$ for humans will suffice if accompanied by the therapeutic index for pethidine via IV of another species.

Pethidine is an opioid painkiller with approximately $\frac{1}{7}-\frac{1}{8}$ the strength of morphine and a definite influence on monoaminergic neurons.

I imagine it'd be in the neighbourhood of 30-100, like most opioids that have been implemented in medicine.


texts: What determines the size and shape of a cell? They differ at different tissues / organs/ species


texts: Gray feather with red tip, about 5 cm (2 in) total length. It was found in Lexington, Kentucky (central western USA).


texts:
DNA replication seems so mechanical- the DNA polymerase just running along the template strand. I just don't understand how mutations can arise. When it comes to substitutions, I get that a wrong nucleotide may just bind and it won't be as strong a binding as with the complementary base, but I suppose it can happen. However when it comes to mutations such as insertions or deletions, I dont understand how the DNA polymerase could just skip a section of the DNA or add in extra bases. Chromosome translocation also seems like a mystery to me- almost as if the cell believes it should undergo meiosis but with the wrong chromosomes paired up and it only occurs with one pair...

I realise that this is quite a broad question, but any information on the mechanism of how mutations occur would be much appreciated :)


texts: How to determine suitable Cysteine mutations?

texts:
In the lab, I'd like to generate a dimer of a protein via disulfide bonds. The interface between the two looks as follows:

Now, in the interface, there isn't any cystein I could use to dimerize the two, so I'll introduce some (bacterial transformation). But which place would be the best to introduce them? Probably not the alpha-helices or beta-sheets. But is there a general method to find the best linking site? Maybe there are program to calculate an energy minimum? Or is there a nice heuristic?

Here  a picture of a close-up of the interface.


texts: Can base editors be anything else than SpCas9 and SaCas9 variants?

texts:
I found out that only variants of Streptococcus pyogenes Cas9 (SpCas9) and Staphylococcus aureus Cas9 (SaCas9) are used with adenine or cytidine base editors, and I was wondering why.
Can Neisseria Cas9 be fused to adenine or cytidine base editors as well?


texts:
In  gymnosperms the plant body is predominantly sporophytic. It produces microspores or megaspores my textbook says that these undergo reduction division in order to form male gametophytes pollen grains and female gametophytes that is egg.

The thought of a spore being diploid is revolting, as I have learned in the case of bryophytes and pteridophytes that it's haploid. Can anyone help me asap.


texts: Is there a definition of species where Lions and Tigers are the same species?

texts:
According to Species concepts

  There are at least 26 recognized species concepts

And according to Why are lions and tigers considered different species (not sure how reliable this source is though, but I've seen exactly the same answer in another website)

  The reason tigers and lions are different species is because of different behaviours, different habitats, different social hierarchies, and they each have their own subset of genes that they share within their species (like the genes for stripped fur or for manes).

Now, I'm not sure about "social hierarchies" (which I'm sure it's a fuzzy concept) , but there are different breeds of dogs with different behaviors, living in different habitats, and there has to be differences in genes in different breeds, since even in humans populations there are 1% of differences in genes and according to other sources more.  Then my question is, since Tigers and Lions are closed to each other to the point they can produce offsprings, is there any of those 26 definitions of species where lions and tigers are the same species?


texts: Why does air from the nasal cavity not go into the oesophagus?

texts: When we ingest food, the epiglottis covers the trachea and the uvula covers the nasal passage. But what happens when we breathe? Why does the air go into our trachea and not the oesophagus?


texts:
I am try to review my scope work, since my proffesor asked me to calibrate all the scopes for an intro class in biology, and it has been awhile since I used one. I googled "Binocular microscope use" and saw a powerpoint as my first link.

On page 21 it stated:

  The diaphragm should be opened just enough to allow the objective lens
  to collect all of the light that comes through the sample. Opening the
  diaphragm too wide, allows some of the light to escape collection by
  the objective lens. Closing the diaphragm too much, causes aberrations
  of the image.

But if the diaphragm controls the amount of light passed through, why is "light escaping" a bad thing? Why cant I keep the light as wide as possible?

As an aside, if anyone has any suggestions for review on binoc. compound microscope use, I would appreciate it.


texts: Why does the upper respiratory tract not fill with water when diving?

texts:
When we swim, I know we close the some of the vestibular folds in the larynx part of the throat to hold our breath (and to avoid water from getting into the lower respiratory tract, I suppose).

I wondered, what avoids water from running into the upper respiratory tract (such as the nasal cavity and pharynx), when we e.g. dive to the bottom of a swimming pool and lie on our back on the bottom of the pool?

I've tried googling for an hour (during which I learned most of the above anatomical words), but I have not been able to find any bodily mechanic that prevents water from entering the nasal cavity... How does the body avoid this, since there is clearly two holes in our nose, which could lead to water filling our whole upper respiratory tract, if they are not closed?

Thanks!


texts: How can one determine how much of a region flanking an RNA sequence of interest to include in order to look for interfering secondary structures?

texts:
I have a set of RNA sequences, and I have been analyzing slices (i.e. target frames) of these sequences in order to determine whether they conform to certain structural criteria. One of these criteria requires that both the target frame of the RNA sequence and its flanking regions have as few secondary structures as possible, i.e. that the RNA nucleotides flanking the slice are as linear as possible.

Using Python and a number of standalone executables, I have been calculating the minimum free energy and optimal structural conformations of the RNA sequences and their flanking regions (see here for more details: http://math.mit.edu/classes/18.417/Slides/rna-prediction-zuker.pdf), but I realized that there is a slight hiccup in my current approach. Namely, I determine the secondary structures of the flanking regions as though they were sequences isolated from my target frame of interest. Now, given that the whole is more than just the sum its parts, I do not know if the secondary structures that are determined when the flanking region is examined on its own versus when the flanking region is examined including either a part or the whole target frame are the same.

Right now my code evaluates 20 nucleotides up and downstream of the target frame as the flanking regions, but should I instead, for example, evaluate 20 nucleotides up and downstream plus some nucleotides of my target frame? Right now, my target frame is 120 nucleotides long, so it might be worthwhile to consider 10 or 20 nucleotides of my target frame that are attached to the flanking regions. But I'm not sure how many nucleotides from my target length should be considered in order for the number of secondary structures to be consistent in the flanking regions. Or is this approach somehow faulty?


texts: I found this in my refrigerator water filter. Is it a biofilm? Is it a sign of dangerous bacteria?

texts: When I dispense water form my refrigerator after changing my filter, the following slimy tube like deposits appeared. Does anybody know what this is? Could it be a biofilm growing in the water hose, and if so, is this type of bacteria likely dangerous or benign?


texts: What is the appropriate method to send a strain?

texts: We are planning to send an ecoli strain to another lab. What is the appropriate way to do so. No MTA is required but the options seem to be using filter paper or sending a glycerol stock on dry ice.


texts: If my sunglasses provide "100% UVA/UVB Protection" why can't look directly at the sun?

texts: Is it simply the amount of visible light entering the eye? I'm simply confused as to why experts say that sunglasses do not provide adequate protection when they are advertised as blocking 100% of the sun's harmful rays.


texts: Why does my grass luminesce when I step on it?

texts:
I live in Austin Texas. My grass is in pretty bad shape but I have noticed small luminous spots on some areas after I step on them.

I'm guessing this will be seasonal so, for the record, this is during November and December that I've noticed it.  It's been quite wet and about 40F to 60F at night. I've seen it a dozen times over the last several weeks. I've attempted to collect samples and when I bring it inside to study it, there is nothing there but grass and maybe some young root systems.  I've googled and haven't seen anything like this discussed.  Does anybody have an explanation?

I can see about 5 spots after trampling a few square feet of my grass.  Using a DSLR and a time exposure, this is the best photo I've been able to get of one:

On one attempt, I pinched the glowy part, held it in my hand, confirmed it was glowing, brought it inside, and this is what I had:

Can anyone explain this?  Is this significant?  Or perhaps the right question is where should I go for a question like this?


texts: How many molecules are generally required for cell signallng processes for given cases?

texts:
I know its really a broad topic but I am interested in just few cases:

Quorum sensing
neurotransmitters for the communication of images/ general information
hormones/pheromones

I actually want to know that does a single or hundreds of molecules are needed to communicate information from one cell to another.
I searched but approx number of molecules, I can't find anywhere.


texts: Where can I find the genome of the L-strain coronavirus and the S-strain coronavirus?

texts:
I read an interesting article about two strains of the coronavirus:
https://www.newscientist.com/article/2236544-coronavirus-are-there-two-strains-and-is-one-more-deadly/

I would like to know how the scientists used to classify a coronavirus as l-strain and s-strain.
And more specifically I would like to have the genome(The DNA) for a l-strain and a s-strain.


texts: Are there foods which not only prevent but help fighting cancer?

texts:
I was reading a probably not to serious webpage and I found this quote

  " Certain types of vegetables, such as the cruciferous variety, are
  not only nutrient-dense but contain compounds that may fight cancer,
  according to the National Cancer Institute."

Then I looked more information about this, but I can only find references to foods helping prevent cancer but they dont seem to say they help fight cancer when it's already present.

This page says the following foods help prevent cancer, but later make an ambiguos statement that you could think they imply those foods help fighting cancer when it's presented

  The following is a list of foods that have been shown to have
  cancer-fighting properties. While some are well-known super foods,
  others may surprise you. You won’t find a burger or fries on this list
  – when it comes to cancer prevention, clean eating prevails:

http://www.cancercenter.com/community/newsletter/article/Foods-that-have-cancer-fighting-properties/

So, my question is, are there foods which not only prevent but help fighting cancer when it already exists?


texts: How does the eye know whether to focus further out or nearer in order to bring a blurry object into focus?

texts:
If the eye sees an object, but the object is out of focus, the eye could be focusing too near or too far. How does the eye (or the brain) distinguish one situation from the other?
How does it know whether to focus closer or further?

I'm interested in the case when:

only one eye is open (There must be another way besides parallax clues).
The object is an unfamiliar size
The object is an unknown distance from the eye.

Ideas so far

Does the eye try focusing either a little nearer or further and then if that doesn't help to make the object clearer then the eye focuses in the opposite direction?

Or is there some light-sensitive apparatus that is always a focused a little nearer or further than the rest of the eye, and so for instance if the cells which are focused further out are giving a clearer picture than the other cells then the eye knows to focus further out?

Or is the blurriness of a object closer than the focal point a distinguishably different sort of blurriness than an object beyond than the focal point?

Or is there some other mechanism altogether?


texts: Did spiders respond to light for building webs before artificial light was invented?

texts:
I have noticed that during summer, beautiful spider colonies grow wherever a strong light is:

I'm wonder whether spiders evolved to seek naturally lighted areas where they build nests (before artificial lights) or if they always had the ability to seek places full of juicy insects - and in cities this ability just leads them to lights.


texts: Multiplex PCR, shorter amplicon inhibiting longer amplicon?

texts:
I want to run multiplex PCRs for my genotyping, with a primer pair targeting my construct and a primer pair targeting some housekeeping gene (sort of a built-in control).

I designed the control amplicon to be very short (I tested 3 primer pairs with ~120, 85, and ~50bp amplicons respectively). The main rationale behind this being that usually my amplicons are ~200-400bp, and I want something clearly distinguishable, but shorter rather than longer (I want to keep my options open for longer target amplicons).

In any case, regardless which control primer pair I use, whenever I try to multiplex I only end up seeing the shorter amplicon. See the gel picture below for an example (lanes: 1-ladder, 2,3-target+control, 4,5-control, 5,6- target).

I see that lanes 2,3 have a very faint additional smear compared to 4,5, but I want a band for my target amplicon. Also, my shorter bands are quite blurred.

Also, just for reference, my amplicons do not overlap at all.

So, I guess my questions are:

Why is the longer band disappearing?
Why is the shorter band so blurred?
What can I do to prevent this form happening?


texts:
Given what we know of the genetics of eye color and their historical distribution, is it possible or at least plausible for a person born in the Horn of Africa during the early Neolithic (ca. 9000 BCE), assuming no recent ancestors from outside this area, to have had amber eyes (or in general anything other than brown?) If so, would one or both parents need to have that color as well, and what of siblings?

I know that today there is much less isolation and much more crossing of genetic lines, so that pretty much any combination of skin and eye color is likely possible, but no doubt it was different back then.


texts: DNA strand displacement and Branch migration- the same or different or interrelated?

texts:
So, recently I have begun studying DNA strand displacement and then I come across the term 'branch migration' (p.s. I am not a biology major student). What I understand is that branch migration is part of the strand displacement process.

Or is it not? If branch migration is not a part of strand displacement, then what is it?
First, does strand displacement refer to the case where a single-strand
(floating freely) is competing with the incumbent strand to pair with the complementary pair, resulting in the displacement of the incumbent strand?
That means we have one DNA complex and one single-strand in the input and output. And second, does branch migration refers to the case where two DNA complexes exchange strands, resulting in two DNA complexes both in the input and output?

To me, both processes are involved in the displacement of strands (but I can't seem to find their differences).

Can someone kindly explain to me their difference, if there are any?


texts: How to perform a DNA structural alignment in pymol

texts:
How can I "fit" two DNA structures having different nucleotide sequences in PyMol?

I would like to use the structure of a DNA-binding protein in PDB (1h9t), which is bound to DNA in the PDB file, and fit a longer DNA built in silico with a 3D dart (haddock.science.uu.nl/dna/dna.php).


texts:
This may be a strange question, but does anyone know what kind of tree this could be?

I know, it's just a comic, but these trees, at “walking distance” within that comic are easily identifiable as Grandidier's Baobabs:

(That might indicate, of course, that the above tree also occurs on Madagascar, but it's a comic, so all bets are off.  And yes, we know, there are no squirrels on Madagascar.)


texts:
I recently purchased some Maltose Binding Protein and as the name suggests this protein binds to maltose. The problem I have is the protein arrive with maltose bound. I know this through native mass spectrometry analysis.

Is there a way of removing the maltose bound to my protein sample while also keeping the protein in its native state?

Examples of two states from the PDB can be seen here: Bound and unbound


texts:
I live in Denmark, Europe and was going for a walk on a beautiful cemetary in the city. I saw this tree and would like to know what species it is.

Unfortunately i have no photos of the tree from a closer distance.


texts: Why is polysome loading affected by double stranded structure?

texts: Why polysomes are not able to load properly onto a transcript if a transcript has a double-stranded structure in it?


texts: Enzymatic Protein Deglycosylation of TCL

texts:
I've done O- and N- linked enzymatic deglycosylation of purified and lyophilized proteins. Following some modifications to the manufacture's protocol, I had great results.

I now want a student to deglycosylate some total cell lysates (TCL) of infected cells.  Can he just Vacufuge/vac-spin Triton-X  TCL's and then proceed with the deglycosylation?  The first step is often resuspend in water.  I'm wondering if ether the salts would need be removed by dialysis, or if it doesn't matter, if he can start just from the lysate.

The antibodies we have for western detection are excellent, so that is unlikely to be a limiting factor.


texts: Can you tell me what species of insect this is?

texts:
I live in Verona, Italy.
Today I found this black insect and I don't know what species it is. My mom claims it's a kind of mint but I don't think so.


texts: Is blood pressure in the aorta and brachial artery the same or different?

texts:
Does the blood pressure at the root of aorta equal the blood pressure in the brachial artery?

I've heard it does, but it doesn't quite seem to make sense as I'd think the blood pressure would be lowered the further it travels?


texts: How to differentiate male and female mosquitoes at pupal stage?

texts: There are many differences between male and female mosquitoes in their adult stage. But for my experiment, I need mosquitoes before they mate. So I need to sort them before they develop in to an adult. The best option is to sort them in their pupal or larval stage. I tried to search the differences, but most of them were very general. So, if someone knows about it, please share your answers.


texts: Can someone identify this plant I saw in NYC (might not be native idk)

texts: I've never seen a plant with these type of leaves before and was wondering if anyone recognized/can figure out the species.


texts: Are there people who can change one of their eyes' depth of focus, while not changing the other eye's?

texts:
Are there people who can change one of their eyes' depth of focus, while not changing the other eye's depth of focus, without any surgical or other external mechanical intervention?

Edit: let's assume both eyes are functional and not obstructed.


texts: What is the exact definition of mitochondrial depolarization?

texts:
As I understand as per literature reading and some khanacademy(https://www.youtube.com/watch?v=PtKAeihnbv0&t=315s):
Proton gradient := the gradient created when hydrogen ions moves to the intermembrane space from the mitochondrial matrix.
Mitochondrial membrane potential := the potential energy created by the proton gradient.
Does depolarization mean the loss of mitochondrial membrane potential? The lower the mitochondrial membrane potential, then the more depolarized the mitochondria?
So the way I defined proton gradient and mitochondrial potential is conceptually derived from the so-called proton-motive force used here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2605959/ and also described here https://www.dummies.com/education/science/biology/the-proton-motive-force/ as an electrochemical force. Thus, my definition is from my rudimentary physico-chemical intuition.


texts: If evolution is true, how do all organisms have varying amount of chromosomes?

texts: I thought genetic mutation changes genes and therefore evolution happens, but it doesn't explain how  chromosomes are created/removed if the first organism had a set amount and now all the organisms have different numbers of chromosomes. How does this happen?


texts: How is the subunit molecular weight different from the native molecular weight?

texts:
I noticed that the native molecular weight for an enzyme is different from its subunit molecular weight. Why are they different? Aren't the genes needed to express the enzyme the same in the native organism and in the heterologous expression system?

Does the heterologous expression system happen to affect the molecular weight of the final enzyme product? If so, how?


texts: What were the camels' humps good for back in the polar areas?

texts:
I've heard that camels lived in the North America formerly and just in the last few thousands years they've migrated to the hot deserts. Thus they allegedly utilized the adaptations against the cold weather in the tropics.

One of this adaptations have been their humps. Clearly, it is useful not to have a thick fat layer all over your body in the hot weather. (I see it like a neural spine sail (which helps with thermoregulation to the desert fauna).) But how about the polar areas? All the other polar animals don't see to be restricted by the fact they save all the fat under their skin in any way.

So what were the original reason for the evolution of the camels' humps?


texts: If alleles occur at the same locus on a chromosome, does that mean they are of the same size? I was under the impression that they were, but I saw a gel electrophoresis testing different alleles of the same gene and saw them separate. I don’t understand how they could separate if they are of the same size, but if they aren’t, then how can they be housed in the exact same locus?


texts: Gene located on Which strand? Want reference.

texts:
Update: Initially my question (below) was appropriately marked as duplicate/overlapping  with two other questions; This and this ; among them a specific part of an answer of the second duplicate/overlap ; appropriately answer my question.

  The convention is that in indicating any sequence feature† in a protein-coding gene on double-stranded DNA, a single strand‡ is represented — the one from which the amino sequence could be read using the genetic code (conceptually, with T substituted for U). Like any other nucleic acid sequence§, it is always written in the 5ʹ to 3ʹ direction in the same manner as the mRNA transcribed from it, without this being explicitly stated.

But what it does not mention (but I'm still looking for); is whether there is a standard and universal documentation for this particular convention (IUPAC/ IUBMB/ ICBN/ ICZN/ anything such); because "conventions" are human-made rules, and without "declared, universally followed, and accessible" documentation; the conventions does not make a sense.  It rather feels like a rumor or viral phenomenon.  I visited the IUPAC and IUBMB website home pages but I could not locate the documentation from there. Also google keyword search did not found the helpful.

So I specify my question that I want to get the standard/ official source of this convention. I would be highly grateful if anyone kindly mention the source hyperlink.

My Initial Question

I'm stuck at a very basic convention on notation on reading Gene sequence. *Specially when a  book (or question paper or anything) does not mention whether a  nucleic acid (usually DNA), uses a single stranded DNA

The problem appears because similar region of the 2 opposite strands of a DNA can contain different gene, i.e.

(So it is possible that if we note a stretch from gene-1 with its complementary sequence, that complementary sequence could be confused with gene-2.)

In some cases, a sequence to a stretch of nucleic acid, indeed mean the sequence directly.

For example; In the wikipedia image about Reading Frame (Permalink)

the 5'to 3'Left to Right indicates the sequence of the template strand directly whereas

But at the more and more "interior chapters" I've seen a rather complicated and indirect notation (although I could not found  clear mention of a convention anywhere in books or web)... when they mean a sequence of a stretch of a gene (or a regulatory sequence), they writes the "nontemplate" or "sense-strand" sequence of the respective gene.

In the Wikipedia image on TATA Transcription Box (Permalink);

it must be a sequence from the nontemplate strand because if it was the template strand,  the "Promoter" location on the "template" strand must be on 3' side otherwise RNA polymerase would not be able to synthesize the nontemplate strand mRNA strand from 5' to 3' time-order. But it would become impossible to infer for me if the given sequence lacked labelling for relative locations of promoters and structural genes.

Now my question is If an article  provides me a single stranded  "Gene Sequence"; How can I infer it is directly the sequence of the mentioned gene stretch or it is the complementary ("sense") strand of the gene? What is the convention about it?


texts: What is special about Pulse-Amplitude-Modulation (PAM) fluorometry?

texts:
I know that PAM fluorometry is used to measure chlorophyll fluorescence and understand the principle of those measurements.
It is in principle clear to me from prior research in the literature, that we take a dark adapted sample, measure F0, provide an initial pulse of light, that saturates all reaction centers, then measure Fm and then turn on actinic light and provide pulses with lower intensities from time to time.
What I however don't understand are two main points:

What exactly is meant by actinic light (from my own research I only know this light should leave most reaction centers open and allow photochemical quenching to take place)?
How does a PAM fluorometer differ from a common fluorometer and couldn't one just use a normal fluorometer and maybe use external lights for the pulses if the fluorometer isn't able to provide the strength/accurcay needed in the light source?


texts: Transcription when Chromosomes are Condensed

texts:
Are genes transcribed just as well when chromosomes are condensed?

I want to design a screen that depends on genes not transcribed when chromosomes are condensed (to identify cells that can't condense).


texts: Identify a small bug, possibly a plant bug?

texts:
We found this bug in a bedroom in southern California. It's small: the body is about 5mm and the length including legs and antenna could be up to about 10mm. It's mostly black, though the abdomen from the bottom appears to have gold highlights under light when I used a flashlight. In sunlight it appears somewhat brownish. It looks like it has wings which forms sort of an "X" pattern on its back. The legs are dark black or brown but may be somewhat translucent in sunlight to appear an orange-gold color.

What species is it? It looks to me a little like a plant bug (phylinae?) or roach or beetle but I'm not sure. And could this species bite?


texts: How can DNA profiling be used to determine the number of organisms from a specific species that is within a certain area?

texts:
Here is the tedious exam question that asks this: question 8(b).
https://drive.google.com/drive/folders/0B23NLD5L6099VWJya3dfLVJpbmc
The question states:

In 2007, the brown bear was a threatened species in Alberta, Canada. A study was carried out to determine the number of bears in the area. Fur wascollected from trees that the bears had rubbed against and their DNA analysed.
(i) Explain how DNA analysis would help the scientists to determine the number of bears in the area.

The answer simply states:

idea of comparing bands

idea that each bear has unique {DNA / banding patterns}

idea that the number of different banding patterns would equate to the number of different bears

My question is: How does the entire process fit into together?
I am absolutely baffled as to how the entire investigation would fit into each other, and I've been trying to articulate it for hours. It seems like if I'm just going to be collecting fur samples off trees there are going to be cells belonging to different species, then the DNA pattern produced will include a different number of bands from all of the different species. To overcome this problem, I think 'would we somehow separate the different cells into different groups with each group belonging to a specific bear by some technique that isn't DNA profiling and I don't need to know about at high school level? I then reason that we would have accomplished our task of identifying the number of different number of bears present within the sample. How would one identify the different numbers of bears?
The second part of my question is that I don't understand how the different samples from trees and fur will be used in order to estimate the overall population size within the area? The only animal sampling technique that I know of is that capture-recapture method.


texts: What animals stop other members of their species from mating and why?

texts:
(In particular primates)

I know chimps do. Powerful alpha males chimp would beat up omega males that they caught mating.

I know gorillas do. Powerful alpha males gorillas would beat up omega males that they caught mating.

I know humans do. Politically powerful alpha males would jail or stone weaker omega "peasant" humans that they caught mating.

I know bonobo doesn't.

What about other primates/animals?

So what's the difference and why?

Reference:

  The alpha animals are given preference to be the first to eat and the
  first to mate; among some species they are the only animals in the
  pack allowed to mate. Other animals in the community are usually
  killed or ousted if they violate this rule.

http://en.wikipedia.org/wiki/Alpha_%28ethology%29

How do preventing and punishing others from mate improve ones' own gene pool survival? Are there similarity between primates (including humans) in this regard?


texts: Why don't phosphatases both add and remove phosphate groups if enzymes catalyze reactions in both directions?

texts:
We know that Phosphatase is a type of enzymes that removes a phosphate group.

Why can't phosphatases add a phosphate group if we know that all enzymes reactions are reversible ?


texts: What, if any, experimental evidence is there that flies rub their legs together in order to clean them?

texts: Everybody's seen a fly rubbing its hands together like Mr Burns. And almost everybody's heard the standard explanation - that it's cleaning itself. Now, this is certainly a very plausible explanation, but has it been demonstrated? I can't find any references to experiments seeking to prove this hypothesis. I'm asking because, not being very familiar with these matters, I'd love to know what methods were used to demonstrate something like this.


texts: Does capillary blood pressure have any effect on how much oxygen or nutrient gets distributed to tissues?

texts:
From what I have read regarding blood pressure and blood flow, I've come to the conclusion that, apart from the osmolarity of blood, the only determinant of how much oxygen/nutrients the tissues get per unit time, is blood flow.

Does blood pressure (not systemic, but within a theoretical capillary) have absolutely no effect on this, and if so, why? Intuitively, it seems to me that if the force by blood on the walls of a capillary increases, that would imply a higher number of molecules touching endothelial cells, and thus a higher likelihood of molecule transport per unit time.

Or is it perhaps that they both have positive effects on oxygenation/nutrient transport; but blood flow's effect greatly excels that of blood pressure?


texts: How do animals contain and dispose of bacterial endotoxins (lipopolysaccharides)?

texts:
Gram negative bacteria naturally release endotoxins which are lipopolysaccharide molecules. These molecules are toxic to many eukaryote cells, including macrophages. My question is how animal organisms locate, isolate, contain these toxic molecules. For example, if a lipopolysaccharide attaches to a macrophage, thus neutralizing it, does this actually kill the macrophage or just render it inert? In any case, the ineffective macrophage must now be removed as waste. How does that occur?
In the Wikipedia article on endotoxin it reads "Normal human blood serum contains anti-LOS antibodies..." without further describing them. I find this statement strange because normally when I think of antibodies, I think of them attacking cells or organisms, not individual molecules like lipopolysaccharides. What are these anti-LOS antibodies and how do they function?


texts: Variation of fixation probability over time in Wright-Fisher model

texts: In Wright-Fisher model of population size N and initial mutation frequency of 1/N, how does the fixation probability vary over generations. So, mathematically, what is the function that maps the generation to its fixation probability?


texts:
I have tried to find an answer to this but have not found anything after multiple attempts.

The question on the table is if the human body is able to produce an immune response to the COVID-19 virus if one has been exposed? This would apply most specifically to persons that have been tested positive but have "survived" (i.e. not having succumbed to the serious lung complications that have caused deaths for some persons).

A follow on question that comes from this is if the human body is able to mount a suitable defense does the current practice of keeping people in quarantine for two weeks allow for this defense to reach full effectiveness?


texts: Is Homo sapiens the only species capable of prioritization?

texts: Just what the title states--given an absurdly large number of assignments to perform in a limited time-frame we usually attempt to do the most important ones first. Is this ability to define and execute by priority a universal feature in all sentients, or is it a socially learnt behaviour of us Homo sapiens?


texts: How to color based on b-factor for all the frames in one object in Pymol?

texts:
I load a protein.pdb file into Pymol. This file has multiple frames (or states), and with different b-factor values at different frames at the PDB file b-factor columns.

After running the spectrum b command, the colouring is only based on the last state of the object.
So can I colour the frames differently using their corresponding b-factor values? In that case, I can see the colour changing throughout the frame playing.
In case someone wants to create a PDB of multiple frames, you can do like this:
MODEL        1
ATOM ......
ATOM ......
ENDMDL
MODEL        2
ATOM ......
ATOM ......
ENDMDL


texts: Haploview command line: how to get tagSNP

texts:
I am trying to use Haploview command line software to compute haplotypes and extract tagSNP for those. When I use the standalone version on my local computer I tick the 'Show tags in blocks' option so that when I export my haplotypes I get the tagSNP to be marked with '!'.

I am trying to do the same thing with the command line version but can't find how to achieve that. My command is as follow (submitted to Linux running server):

java -XX:+UseParallelGC -XX:ParallelGCThreads=1 -jar haploview.jar -nogui \
                    -pedfile $pedfile \
                    -info $info \
                    -out $out  \
                    -maxDistance 100 \
                    -skipcheck \
                    -missingCutoff 0.5 \
                    -blockoutput GAB \
                    -dprime \
                    -log ${out}.log \
                    -memory 124000 \
                    -aggressiveTagging \
                    -aggressiveNumMarkers 3 \
                    -taglodcutoff 3 \
                    -tagrsqcounts \
                    -tagrsqcutoff 0.8 ;

I manually set arguments to the same value when using the standalone version so the only thing differing seems to be the 'Show tags in blocks' option.

Could you explain me how to get the tags to be marked in the *.GABRIELblocks files or how to do it myself using other output files ?

Thanks a bunch !


texts: If the covid-19 appeared once, could it reappear anytime?

texts:
Governments are imposing confinement measures on their populations, trusting that if there is no more transmission the virus will die out.
But since this coronavirus appeared a first time, what could prevent it from reappearing any number of times ?


texts:
The retrotransposons and certain DNA-transposons, are "jumping" sequences which may be incorporated elsewhere in the genomic DNA of an organism, through varying mechanisms. This insertion is almost random in case of retrotransposons and most DNA-transposons, but some transposing enzymes show specificity in selection of insertion sites. In either case, the "copy-paste" mechanism of transposition is essentially a random process(considering the frequency and place of transposition) and therefore, the extent of transposition should vary among all individuals, and all cells of a single individual. My question is,

  Is the extent of transposition random and varied among the different
  somatic cells of an individual or is there a regulatory mechanism which ensures that
  there is not much difference in the net content of DNA (caused by unequal transposition) by equalizing
  the extent of transposition in different individuals or different
  cells of the same individual? If not, does this unequal c-value in different cell cause any troubles?


texts:
I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.

They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.

So this brings me to my question: how do each of these spots end up with frogs in them?  I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it?


texts:
Spinner dolphins have a behavior where they jump out of the water and spin a bunch of times in the air. Wikipedia's article on this just states

  These spins may serve several functions

and doesn't anything. Are there any known reasons for their extreme spinning behavior?


texts: Maximum heart rate increase/decrease while physically active

texts:
I'm a computer scientist and implementing a heart-rate monitor for physical exercise. While I try to improve my code, I stumbled over the question how fast the heart rate can change within a given time slot.

Let's say someone in rest has a pulse of 60bpm. If he now gets physically active and exploits himself, how much time will it take at least to reach his maximum pulse of (supposed) 200? How long will it take, after hitting that point to slow down his heart rate again?

Or to rephrase the question, so it fit's more to my specific code-problem.
How much can the pulse change (increase/decrease) within a small time-slot of, let's say 8 seconds.

Annotation:

Susan pointed out, that might be dependent on the trainings-state of each individual. If so, what is (might be) the highest possible increase/decrease?
I suppose the pulse increase of a bad trained person might be faster then that of a well trained person, whereas the the decrease of the pulse should be way faster of that trained person.

Annotation 2:

The question was already posted here: How quickly can the human heart rate rise and fall.

But not really answered. The answer here says, the rate can change within one beat. But it does not say by how much it can change, which bothers me. Especially how much it can change within a given period.


texts: Is the Basic Reproduction Number in epidemiology dependent on population size?

texts: I am assuming that the basic reproduction number $R_0$ of a disease depends on the population size (or the number of susceptible individuals). When $R_0$ is reported it seems to be without such information. Is there a standard population size for reporting $R_0$?


texts: As I read in my textbook, aquaporins exclude $H^+$ when absorbing water, but where does this $H^+$ come from? Additionally, is $H_3O^+$ a liquid that looks like regular water?


texts: What’s this bug? Sign of an infestation? Found crawling up the side of my washing machine. [WA]

texts: Just spotted this bug on the side of my washing machine after putting some dirty clothes in the hamper and transferring a damp load to the dryer. I’m hoping it came in from outside somehow, and isn’t some type of vermin (I live in an apartment and I’m probably the cleanest resident in the building. I’m also paranoid about household pests.) It’s very small, photographed against a damp paper towel. Please tell me this is not a baby roach?


texts: why hens determine the sex of the chick?

texts:
So, I have an exercise where I have to correct the second part of the sentence. It goes like this:

  In hens, the sex of the chicken is determined by hen, because the hen is the heterogametic organism

And I really can't find the mistake, please help.
 Also, I'd like to know why hens determine the sex of the chick.


texts: Why does oxygen bind to hemoglobin in an specific angle?

texts: There is an specific angle of the bond between oxygen and hemoglobin in lungs, which I don't know, but what interests me more is the question, why is it specific?


texts: How to derive rate of product formation for an allosterically inhibited enzyme?

texts:
I'm working through Mathematical Modelling in Systems Biology: An Introduction by Brian Ingalls, and in Chapter 3 there's an example of a simple allosterically inhibited enzyme with reaction scheme shown here:

$$\ce{S + E<=>[k_1][k_{-1}] ES->[k_2] E + P}\\[2em]
\ce{I + E<=>[k_3][k_{-3}] EI}\\[2em]
\ce{I + ES<=>[k_3][k_{-3}] ESI}\\[2em]
\ce{S + EI<=>[k_1][k_{-1}] ESI}
$$

where E is the free enzyme, I is the allosteric inhibitor, S is the substrate, P is the product, and ES, ESI, EI etc. are the various complexes between them. The book goes on to state that the rate of formation of P is

$$\frac{V_{max}}{1+I/K_I}\frac{S}{K_M +S}$$

where

$V_\text{max}$ is the maximal rate of reaction ($k_2$ * Total enzyme concentration), $K_I$ is the dissociation constant of the inhibitor $k_{-3}/k_3$ and $K_M$ is $(k_{-1}+k_2)/k_1$

No proof for this is shown, although the book says the solution is assuming a quasi-steady state of the complexes ES, EI and ESI. I've attempted to work it out, and arrived at almost, the same equation, except I have I/Ki * (k-1+k3)/k1 instead of I/Ki * KM. I have no idea how to get to the equation present by the book. Can someone explain how their equation was derived?


texts:
I was recently reading about genetic diseases and came to understand that many of them are caused by de novo mutations in the prezygotic or early embryonic stages of the life cycle of the organism. Most chromosomal aneuplodies resulting in well known genetic diseases such as the downs syndrome caused by trisomy of chromosome 21 are caused due to de novo mutations.
However the thing that I didn't clearly understand was the reason for some de novo defects being more prevalent than others. For example the trisomy of chromosome 21 causing downs syndrome is relatively more common than the trisomy of the other chromosomes. Why are some aneuploidies such as trisomy 21 replicated independently in many different individuals (are more prone to occur) than others?


texts:
After a leaf has fallen from a tree, if it is still green and hasn't dried out, is it still converting CO2 into O2 if not put in water?

Can anyone find any data showing how long any different species of leaf will continue to produce oxygen after fallen?


texts: In a sarcomere, during contraction, is chemical energy turned into elastic energy and then mechanical energy?

texts: I'm familiar with the cross bridge cycle and how the sarcomere contracts, but I have two related questions. I’ve read that when the myosin head cocks, it’s similar to a spring-loaded mousetrap. But is this actually true or just an analogy? In other words, is the chemical energy actually turned into elastic potential energy and then mechanical energy as the myosin head drives forward or am I misunderstanding this? And if this is correct, what is the evolutionary purpose for storing the energy as elastic potential energy? In other words, you could imagine a different configuration, where instead of the hydrolyzation of ATP to ADP + P being used to cock the myosin head into its high energy conformation, stored as elastic energy, and THEN driving the myosin head forward when the cycle is complete, you could envision a configuration where there is no intermediate step of storing the elastic energy. Instead the chemical energy is directly used to move the myosin heads and contract the sarcomere. So why does this intermediate step exist?


texts: Role of the Hypothalmus in the control of Blood Sugar

texts: In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process?


texts: Why do meristematic cells have prominent nuclei and dense cytoplasm?

texts: I've been reading about meristematic cells having prominent nuclei and dense cytoplasm. However, I could not understand why it is that way. Could somebody please explain?


texts: Where can I find a file listing the genetic differences in humans?

texts:
I don't know much about genetics. For an arts project I'm looking for a human genome.
I read that:

Only about 0.1% of the genome is different among individuals, which equates to about 3 million variants (aka mutations) in the average human genome. This means we can make a “diff file” of just the places where any given individual differs from the normal “reference” genome. In practice, this is usually done in a .VCF file format, which in its simplest format looks something like so:
chr20 14370 rs6054257 G A 29 PASS 0|0
Where each line uses ~45 bytes, and you times this by the ~3 million variants in a given genome, and you get a .VCF file size of about 135,000,000 bytes or ~125 megabytes.

Is that correct?
Do you know a database to download a VCF file or something similar? It would be amazing if you could provide a link to the file mentioned above!


texts: Dreadnoughtus: Why are new taxa named using Dog Latin?

texts:
Once upon a time, binomial nomenclature was expected to follow Latin rules: the genus had to be a noun and the species had to be an adjective that agreed with the genus according to Latin rules of adjectival agreement with the noun modified by it. That’s why we have species names like sativus, sativa, and sativum seen again and again, the exact form depending on the genus’s gender.

So if knew a bit of Greek and Latin, you could figure out something about what binomials such as Stegosaurus armatus or Dodecatheon pulchellum might be about.

Enter 2014, and with it such new binomials as the ponderous Dreadnoughtus schrani.  That looks more like Dog Latin than Classical Latin: just tack a few Latinate-looking suffixes to words that cannot be decoded using any known roots from Greek or Latin.

When I first read about it, I honestly thought somebody was making a bad joke. It’s not like the Greeks and Romans never thought of fearing nothing; one might imagine a taxon built out of actual classical roots — perhaps like *Timendumnihil — would have been more universally understandable than the Dog-Latin form Dreadnoughtus we’ve been stuck with.

Is there no requirement that new taxa have classical forms?  Was there ever, and if so, when and why did this change?  Or, if there was not, then why did everybody seem to go along with the scheme for so long?


texts: Does isolation have any effect upon mouse behavior?

texts:
I work with a lot of mice. I don't do any behavioral analysis, I just inject DNA or RNA and do imaging assays. However, I have noticed some effect of isolation on mouse behavior. Normally, the mice are housed in our university's animal facility with no more than 5 mice to a cage. Sometimes, 1 mouse will be put in a cage by itself. When I go to get these lone mice from their cages, they seem more skittish, harder to grab, and more likely to bite me than mice kept in groups.

Additionally, our Office of Animal Resources, which is responsible for getting in the mouse shipments and putting them into cages, has recently changed how our mice are caged, with a group of 4 mice being normal, any leftover mice are put into cages with other mice, making a 5 mouse cage. This means I haven't seen a single mouse in a cage for a while. So I might not be the only one to have noticed an effect of isolation on the animal's health.

I have heard of studies on monkeys by B.F. Skinner, where he induced very severe depression and other psychological issues by isolating them, so I suspect similar studies have been attempted on mice using far more quantitative methods than I've been able to do.


texts: Are fruiting bodies, basidiocarps, heterokaryotic?

texts: In that, if we have a mycelium with genetically compatible hyphae, will the fruiting body created by this mycelium be heterokaryotic, or will it just contain one dikaryotic organism's genetic material?


texts: Root etiology of non-pituitary low T4 and low TSH

texts:
Please note: I'd like to preface this question by stating that this is neither homework nor me seeking medical advice. I am simply trying to understand the biological, physiological root etiology behind various thyroid-related structures.

This question shows research and is not a duplicate.

My undertanding of the pituitary gland is that it will produce TSH when it senses total T4 (not free T4) is low. So if both total T4 and TSH are low, this implies two things:

There is some underlying reason why T4 is low; but moreover...
There is some other (or related) reason as to why TSH is low

In all the literature I can find, the main antagonist in this scenario is a malfunctioning pituitary gland.

So I ask: if the pituitary gland is deemed functional and non-diseased, are there any other root causes for both a low total T4 and a low TSH? Biologicaly/physiologically, how do they work to produce this low level of hormone production?


texts:
As I was reading Griffith's Introduction to genetic analysis this evidence was provided for single DNA makes single chromosome.

Eventually geneticists demonstrated directly that certain chromosomes contain single DNA molecules. One strategy was to use pulsed field gel electrophoresis, a specialized electrophoretic technique for separating very long DNA molecules by size. The extracted DNA of an organism with relatively small chromosomes, such as the fungus Neurospora, is subjected to electrophoresis for long periods of time in this apparatus. The number of bands that appear on the gel is equal to the number of chromosomes (seven, for Neurospora).

(Page 86).

This points to the fact that one chromosome has single DNA. What I want to know is that what evidence is there that each chromosome is not made up of multiple similar sized DNA molecules all coiled together to give a single chromosome so that the number of different types of DNA molecules to number of chromosomes have ratio one to one but one type of DNA molecule's multiple copies makes one chromosome.


texts:
I developed a PCR cycle to amplify a 5.5 kb genomic DNA region in HEK cell line. When I tried to use the same protocol in A375 cell line I had no results but only smear. Can you help me?
Thanks in advance


texts:
Our body does not produce two polyunsaturated fatty acids (PUFA): linoleic acid and alfa-linolenic acid.

I am thinking reasons for it.

Saturated fatty acids have more energy than unsaturated.
Saturated fatty acids do not need NADPH and some many other enzymes as unsaturated in beta oxidation.
This means that less storage places in the body needed to have energy in the form of saturated fatty acids such as for muscles and heart.

There are four main reasons why our body does not use PUFAs as the primary source of the energy but saturated:

PUFAs lower metabolism and interfere with thyroid function
PUFAs spontaneously oxidize, speed up the process of glycation, since too much glucose
PUFAs decrease mitochondrial respiration - more oxygen and CO2, less lactate

where one reason is missing.

One complication of PUFA is

PUFAs promote diabetes, cancer, inflammation and biological stress

which cannot be thought as a reason why our body does not use PUFAs as the primary source of the energy.

There are positive sides of the PUFAs when they are used in other way.
- PUFAs replace trans fats and saturated fats in certain types of foods.
- PUFAs can help your body to eliminate high cholesterol levels
- PUFAs decrease the risk of heart disease

There are also some types of essential fats that your body cannot produce on its own - omega-6 and omega-3 fatty acids.
PUFAs are used to create these.
You can get PUFAs from vegetable oil, fish and nuts for instance.
Balanced diet is essential.

Normal lipid metabolism depends directly on food lipids.
Both the essential fatty acids and right amounts of PUFAs can be obtained from food.
Body converts the essential fatty acids to long PUFAs, which serve as the precursors of prostaglandins and leucotrienes for instance.

There are so many reasons why our body does not produce polyunsaturated fatty acids.

Why our body does not produce polyunsaturated fatty acids?


texts: Why does gaining a hydrogen in biology considered reducing a molecule?

texts: I've learnt in chemistry that gaining electrons means reduction, while losing electrons means oxidation. But why is it in Biology textbooks I sometimes come across the term gaining hydrogen??


texts:
I fail to understand the what exactly is heteroduplex due to unavailability of a suitable diagram. According to wikipidea:

  A heteroduplex is a double-stranded (duplex) molecule of nucleic acid originated through the genetic recombination of single complementary strands derived from different sources, such as from different homologous chromosomes or even from different organisms.

Should the following highlighted structure be called heteroduplex?


texts: Looking for study/genome data for HIV in different organs

texts:
I am looking for a research study or data base that has HIV genome data available in fasta or similar format. Specifically I need genome data of HIV taken from different organs in the same subject. I am interested in studying the way HIV diversifies and changes to infect different organs and in comparing the process across different patients.
If you are familiar with such a study, or if you have general pointers as to where I may find similar data, I would appreciate it very much. I have done a few hours of searching on NCBI GeneBank, but have had no luck.
Thanks!


texts:
Some lizards are famous for their ability to voluntarily shed their tail to elude predators (Autotomy). After a while, the tail will be regenerated, though with slightly different qualities, as visible in this photograph:

(source)

My question: Can this regrown tail be discarded again voluntarily, or is it a one-time feat?


texts:
Is there a recommendation for how long a target sequence for PCR amplification should be?

If there is how do you amplify a target sequence that exceeds the recommended length?


texts: Why is insulin given in type 2 diabetes?

texts:
For this reason "insulin insensitivity", or a decrease in insulin receptor signaling, leads to diabetes mellitus type 2 – the cells are unable to take up glucose, and the result is hyperglycemia (an increase in circulating glucose), and all the sequelae that result from diabetes $^{(1)}$

Also

  Type 2 diabetes is due to insufficient insulin production from beta cells in the setting of insulin resistance. $^{(2)}$

So why don't we give people a medicine which just increases the number of receptors or increases the sensitivity of receptors? Isn't it illogical to give more of insulin for a deficit amount of receptors? So, what is the logic behind giving insulin?


texts: Blackgram leaves. SDS page. Phosphate buffer method

texts: I am doing protein analysis in blackgram leaves by using phosphate buffer method. But I cannot get proper bands on my SDS-PAGE. What should I do to get proper bands?


texts: What are the clotting factors' effect on avascular necrosis development?

texts: Do clotting factors tpa and pai-1 lead to degenerative osteoarthritis in the same way that lupus anticoagulant and prothrombin might? Is one of these pathways particularly detrimental during formation of osteoarthritis or avascular necrosis (if these factors are inhibited or modified in some way)?


texts: Do any nonhuman species have effective ebola immunity?

texts: I've read that ebola is an effective killer in humans because it has the ability to interrupt dendritic cells from manufacturing proteins that cause the immune system to destroy the dendritic cells when they're infected. Do any other animal species have different kinds of dendritic cells that don't get thus interrupted by ebola?


texts: I'm having a hard time understanding what exactly those letters and numbers in the task in the photo below represent, also the task says "Is the blossom formula written correctly?" translated from Lithuanian to English. I would appreciate some guidance.