All Questions

11
votes
4answers
4k views

What nutrients can humans absorb in the mouth?

For instance, I realise being able to absorb simple sugars in the mouth is pivotal in the rapid action of oral glucose gel. Thus I was wondering what nutrients in general can be absorbed directly ...
4
votes
1answer
606 views

What is the average volume of the hippocampus?

I'm trying to find any information on sizes of the hippocampus? Ideally in the average adult male & female brain
9
votes
2answers
1k views

Does Sansevieria trifasciata really absorb Carbon Dioxide at night?

There's a claim that Sansevieria trifasciata (Mother-in-law’s Tongue) generates oxygen from carbon dioxide during the night. This seems surprising to me: that process requires energy; plants generate ...
9
votes
2answers
176 views

Birds placing sticks on train tracks?

I live in a semi-rural area in Germany, close to a park which trains go through every 20 minutes. Today, I saw something that left me perplexed. There is a large population of birds that look like ...
4
votes
1answer
108 views

Why do we yawn?

I've read a new study which suggests that yawning may help you keep a cool head. Also, the findings might hold some hope for sufferers of insomnia, migraines, and even epilepsy. Is there any ...
6
votes
3answers
581 views

Is there any kind of immortality in plants?

I asked a question about immortality of hydra and leaned good things about senescence. Now I like to know about immortality signs in plants. If there is some kind of immortality in plants its process ...
5
votes
2answers
247 views

How to find Exons in mRNA Computationally

I'm having trouble finding a method to find exons in the original DNA sequence used to create the mRNA, even given the sequence of the mRNA, as I cannot find a way to reliably identify the beginning ...
3
votes
2answers
72 views

Why don't we form immunity to some infections?

I read another question, and its answers, about how vaccines work, but I don't see there, and and don't understand, why some infections can, seemingly, not be immunized against at all. For example, ...
3
votes
1answer
237 views

The fundamental importance of R.E.M. Sleep. (Rapid Eye Movement)

Question: I know that experiments have been conducted to determine the importance of R.E.M. sleep in our sleep cycle. It is particularly important for learning, information synthesis, and recovery ...
2
votes
1answer
123 views

Why do cells have an average 'life span'

I've heard of Henrietta Lacks. As a result of a genetic mutation, her cells never died. I've heard/read that overtime, our cells stop multiplying as much, (as an effect of aging). Why? Why do we age? ...
2
votes
1answer
44 views

What is the point of being selection-free?

I'm reading "Highly efficient endogenous human gene correction using designed zinc finger nucleases" by Urnov et al. They propose a way to use zinc finger proteins for gene therapy. They repeatedly ...
3
votes
1answer
53 views

What accounts for size variation in breeds of dogs?

My assumption is that dogs vary so much in size because of artificial selection pressures coming from human breeders, but are there genetic loci that roughly determine approximate size? Do other ...
3
votes
2answers
213 views

What software is there available for Quantitative structure–activity relationship (QSAR) pharmacological studies?

QSAR modelling in pharmacology basically hangs on using mathematical modelling to approximate the effects different molecules will have on various pharmacological targets. I would like to know what ...
1
vote
1answer
184 views

What is the best way to read and normalize large amounts of Agilent data into R? [closed]

I have a large amount of Agilent data (580 text files that are ~200 MB in size each) that I'd like to normalize. I've run into a problem in that my machine (with 8 GB of memory) still runs out of ...
1
vote
1answer
173 views

are female bonobos “always” pregnant?

Given that bonobo chimps are more sexually active then humans, are the females almost always pregnant? if not how not? also are they so sexually active in the wild as well or is it just in captivity? ...
3
votes
1answer
108 views

Do serotonergic (5-HT2A-mediated) psychedelics elicit stimulant effects?

I know that 5-HT2A partial agonism is the key mechanism of action of serotonergic psychedelics but I also know that some research (e.g. the selective (no activity on any other known receptor sites) ...
5
votes
1answer
84 views

Resource for model organism anatomy/physiology for biological experiments

I'm looking for a resource that best surveys the anatomy and physiology of common genetic model organisms, and how their characteristics are particularly useful for biological experiments. For ...
3
votes
0answers
37 views

Are all Autoreceptors Downregulated by their Respective Endogenous Ligands?

I know that the 5-HT1A and $\alpha$2 adrenoreceptors receptors serve as autoreceptors for serotonin (5-HT) and norepinephrine respectively and are down-regulated by repeat exposure to their respective ...
5
votes
1answer
248 views

Why do antidepressants have a delayed onset of action?

Why do antidepressants take so long to reach efficacy? I've read of theories about it perhaps being due to the strength of negative feedback via serotonergic and adrenergic autoreceptors during the ...
4
votes
1answer
262 views

Why am I getting low transformation efficiency with DB3.1 E.coli cells?

I am making competent cells using DB3.1 E. coli cells. Even after following the exact protocol (Inoue method for ultracompetent cells) given in 'Sambrook and Russel', I am not getting transformation ...
8
votes
2answers
141 views

How can a three-base codon evolve from a two-base codon?

Inspired by this question among others. It's widely suggested that the current 3-base codon system of encoding protein sequences in DNA evolved from an earlier 2-base codon system. This makes sense ...
3
votes
1answer
150 views

Which Receptors are Involved in the antidepressant effects of SSRIs?

From what I've read the major receptor subtypes involved in the antidepressant effects of SSRIs are: 5-HT1A 5-HT2C 5-HT3 5-HT6 Please cite journal articles to back up your claims, I don't want any ...
2
votes
1answer
107 views

Why do genitals feel frozen when freefalling?

I don't want to add much more about that. Since childhood I noticed a chilling effect, even when doing rollercoaster-type activities.
1
vote
0answers
22 views

Which Receptors are involved in Psychedelia/Psychosis?

Which receptors are involved in Psychedelia/Psychosis? I know that the 5-HT2A, 5-HT3, D2, κ-opioid and NMDA receptors are likely involved in psychosis.
3
votes
1answer
47 views

How does Serotonergic (5-HT2A mediated) Psychedelia work?

How does serotonergic (5-HT2A specific) psychedelia work? I've read that there are some theories that it might involve the induction of a glutamate release in certain regions of the brain involved in ...
2
votes
1answer
77 views

Colloids in digestion

I am looking for examples of colloids involved in digestion for a cross-curricular (bio-chem-physics) lesson plan. Although I have found references implicating colloids in both lipid and protein ...
3
votes
2answers
911 views

Why do some animals have 8 Limbs (e.g. Spiders, Octopuses)?

Octopuses have 8 tentacles, spiders have 8 legs. Is there something special about 8? It seems like an animal that needs 360° mobility has 8 legs.
4
votes
1answer
288 views

How does the eugeroic modafinil work?

How does the drug, modafinil (Provigil), exert its eugeroic (wakefulness-promoting) effects? I've read that it works by increasing dopamine and histamine concentrations in the CNS and by serving as a ...
2
votes
1answer
93 views

Do SSRIs downregulate or upregulate the 5-HT3 receptor?

What effect do SSRIs have on the expression of the ligand-gated ion channel, the 5-HT3 receptor?
1
vote
0answers
85 views

Why does trans fat decrease hdl's?

I understand that cis fats increases hdl's, and unsaturated fat increases ldl's, but trans fat increases hdl's and it decreases ldl's. Why does trans fat do this?
3
votes
0answers
68 views

Microscopy Book Suggestions

I've learned programming through great book recommendations, many from the Stack Exchange series of sites. I'm hoping to take this approach to gaining a fundamental understanding of how fluorescence ...
10
votes
3answers
644 views

Mathematical Modelling of Natural Selection

I'm a math undergrad looking for some papers on modelling the process of natural selection. The only paper I've been able to find is by the pre-eminent mathematician Herbert Wilf from 2010, There's ...
2
votes
0answers
28 views

Which of the nicotinic acetylcholine receptors (nAChRs) catalyse the release of the neuromodulators mentioned below that's caused by nicotine?

Neuromodulators: acetylcholine, norepinephrine, epinephrine, vasopressin, histamine, arginine, serotonin, dopamine, autocrine agents, and $\beta$-endorphin. I am aware that agonists of the $\alpha_7 ...
13
votes
2answers
2k views

How many organisms have ever lived on Earth?

I've looked for some information on this, but couldn't find anything useful. Has there been any noteworthy attempt to estimate the sum amount of individuals of all species that have ever lived on ...
5
votes
1answer
557 views

Is human face more resistant to cold than other body parts?

Walking outside tonight in -15˚C I realized an interesting observation: While I felt cold on most part of my body, my face (although the only uncovered part) didn't really feel cold. It registered the ...
4
votes
3answers
5k views

Why are 3 nucleotides used as codons for amino-acid mapping in DNA?

DNA is made of 4 unique nucleotides. When coding for a protein, a sequence of 3 nucleotides is used to code for each amino acid. Why are codons 3 nucleotides in length? A related question can be ...
8
votes
1answer
226 views

What prevents a pregnant woman's immune system from recognizing her fetus as nonself (and attacking)?

I'm familiar with the scenario of Rh- mother with Rh+ fetus having complications (more so after her first child), but that's not what I'm curious about. I want to know mechanistically why a pregnant ...
5
votes
0answers
90 views

Do mammals develop tolerance to anticholinergics?

I know that first generation H1 antagonists, commonly known as antihistamines have anticholinergic effects. Their sedative side effects go away due to tolerance, but as for their anticholinergic side ...
14
votes
1answer
336 views

Fibonacci sequence in nature, truth or just wishful thinking?

I'm reading a bit on the Fibonacci sequence in nature, be it the golden ratio or the golden spiral forming over and over again in biological structures, and then I came across this online article by ...
5
votes
1answer
130 views

functional hypocholesterolemia due to very high HDL or low LDL?

Nutritional and medical recommendations about cholesterol seem to focus exclusively on hypercholesterolemia, and as such, they provide only a maximum desirable level for LDL and a minimum for HDL. ...
4
votes
1answer
71 views

Is there a scientific proof that smoking spoils face skin?

I saw that cigarettes-smokers (more than 3 cigarettes per day) often have the skin of the face which is a little bit spoiled. Is there any scientific proof that cigarette smoke (or the nicotine ...
4
votes
2answers
304 views

Extraretinal photoreception in mammals? [duplicate]

A Finnish firm Valkee sells light-ear-plugs against thing such as jetlag. I asked a researcher in Aalto university how do they really work and he responded ...
5
votes
1answer
130 views

Can in the case of multiple sclerosis (MS), a too high osmotic pressure in the nerve, lead to a high intracellular concentration of potassium?

Can in the case of multiple sclerosis (MS), a too high osmotic pressure in the nerve, lead to a high intracellular concentration of potassium, and also lead to 'pumping up' of nerve cells, which then ...
15
votes
2answers
4k views

Why is cold water more refreshing than warm water?

Obviously, the temperature of water does not affect its chemical composition. At least not in the ranges we are likely to drink it in. Yet it is clearly far more pleasant and refreshing to drink cool ...
6
votes
1answer
115 views

Long term effects of “brain freeze” on the cerebral vasculature

According to one theory, ice cream headaches are caused by an increase in blood volume of the anterior cerebral artery: Another theory into the cause of ice-cream headaches is explained by ...
3
votes
1answer
54 views

Is copy number variation dynamic?

Is there any evidence showing that copy number variation changes over time? I'm wanting to model interactions in expression level as a dynamic bayesian network, but an assumption my approach will need ...
2
votes
1answer
178 views

Why do marine animals have fins?

Why do Marine animals have fins.
6
votes
3answers
375 views

Why people like to see pornographic scenes, but do not feel the same about eating scenes?

This question may seem funny, but I think biology must have good answers. I think no more explanation is needed. I really thought about this and searched for an answer, but there is nothing yet. If ...
5
votes
2answers
54 views

Prostaglandin F2-alpha production in men

I am trying to find information on Prostaglandin F2-alpha, specificaly production in men. Could somebody explain how this prostaglandin is produced? What types of cells are producing it, production ...
2
votes
1answer
337 views

Where does Taq polymerase migrate during electrophoresis?

Assuming a 1% Agarose gel with TAE. Follow up questions: Is there a way to stain for it? Could the polymerase be captured and reused?

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