All Questions

1
vote
0answers
110 views

How does geography affect morphological features of the human body

I've seen many times how a person born in one place, goes to another country for a long time, and then they start looking more like the people there, but I never found out how it works. This report ...
2
votes
1answer
6k views

Why are bacteria and archaea in different domains?

As I understand it, the main difference between the Bacteria and the Eucaryota domains are that eukaryotes have a nucleus and bacteria don't. I understand that bacteria and archaebacteria have enough ...
9
votes
2answers
5k views

Why is PEG important for efficient yeast transformation?

One way to do an yeast transformation is by using lithium acetate, a single-stranded carrier DNA, and PEG (1). I was wondering why is the polyethylene glycol important for the efficient ...
1
vote
1answer
3k views

How does inorganic phosphate inhibit alkaline phosphatase?

I want to know how is inorganic phosphate able to inhibit alkaline phosphatase.
2
votes
1answer
90 views

The oldest common ancesstor of all human beings

Do all human beings have a single oldest ancestor (a man and a woman), or were there were many ancestors at the same time at different places on earth? This article sheds some light. Is there another ...
5
votes
2answers
2k views

What is the function of nodes of Ranvier in axons?

In a neuroscience class I'm taking, it was explained that myelin covers axons in sections, the uncovered sections are called nodes of Ranvier, and signals propagate much faster in the covered ...
3
votes
1answer
708 views

How does sugar enter neurons if they don't use insulin?

I heard somewhere that as opposed to other cells, neurons do not use insulin to get their sugar supply. Why is that? What is the alternative mechanism? I assume sugar can't just enter the cell ...
0
votes
1answer
87 views

Which Enzymes Catalyse the Deacetylation of Drugs in the Human Body?

If you would like more specifics seeing how I realise that this question is very broad and may be difficult to answer in general then hopefully the following will help you out: I am particularly ...
2
votes
0answers
65 views

Why do animals sleep [duplicate]

Animals spend a good portion of every day doing nothing, and it seems like that time could be better spent hunting, searching for mates, etc. Also, animals are not aware during sleep, so it would be ...
14
votes
4answers
1k views

Can two humans with 44 chromosomes produce viable offspring?

It is known that there are very few individuals having 44 chromosomes, not the usual 46 chromosomes. One example is a male in China: the first article, the second article. The other is a female in ...
2
votes
1answer
124 views

How long does a tan last?

How long do melanocytes and melanosomes continue to protect DNA after UV exposure? Basically, if skin is tanned, then over the next month it is shed, will melanocytes continue to produce high levels ...
2
votes
2answers
471 views

Iron deficiency anemia symptoms explanation

In my classes and on the internet, brittle nails and dry hair (or hair loss) are described as symptoms of iron deficiency anemia, but none explains the cause of such symptoms. Does anyone have any ...
9
votes
2answers
1k views

What is Peter's rule in neuroscience?

I have heard and read about Peter's rule informally in the past, but never saw a formal definition or description. Informally I have learned to understand Peter's rule as the assumed correlation ...
2
votes
0answers
44 views

Can Infant Crocodiles digest Bread?

I'm just curious as to whether crocodiles and if you require specifics, saltwater crocodiles, could eat bread as infants. I was watching Lake Placid and I was curious as to whether infant saltwater ...
2
votes
1answer
174 views

Two brown-haired people have two children, P and Q. P has blond hair. Q has brown hair. What is the probability that Q is heterozygous?

Two brown-haired people have two children, P and Q. P has blond hair. We therefore believe that each parent is heterozygous and that blond hair is a recessive trait. Q has brown hair. What is the ...
1
vote
0answers
25 views

What are the conditions that must be satisfied in order for drugs to be deliverable via the epidural route?

I ask this because I've read that while pentazocine is approved by the FDA for the treatment of labour pain, epidural administration is not listed as one of its means of administration (which thing I ...
2
votes
2answers
270 views

What's a good and reliable database on the pharmacodynamic and pharmacokinetic data of drugs both approved and unapproved?

What's a good and reliable database for the pharmacodynamic and pharmacokinetic data of drugs both approved (in the US and elsewhere) and unapproved?
2
votes
1answer
241 views

Copper for cell incubator to prevent contamination

For some reason the lab seems to have a problem with contamination every so often. It's virtually impossible to prevent bacteria, viruses, fungi, etc. from getting into the incubator every time you ...
10
votes
1answer
498 views

Is there are evolutionary explanation for why humans and primates are ticklish? How might it have evolved?

Tickling is a rather interesting phenomenon: When humans or apes are touched in certain areas like the armpits or sides, we respond with laughter AND frantic attempts to stop the assault. Obviously ...
1
vote
2answers
153 views

What gives observable light its colors? [duplicate]

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 ...
3
votes
1answer
249 views

What factors govern the variable age of onset in Huntington's Disease?

"Huntington's disease (HD) is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems." As we all know, this genetic disease ...
2
votes
2answers
133 views

How does your body know when it is infected so it can invoke a fever?

How does your body know when it is infected with a virus or bacteria so it can invoke a fever or ramp up the immune system?
2
votes
1answer
350 views

Can animals use the nitrogen in chitin to build proteins?

Fungi and insects contain chitin, which is about 6% nitrogen. Can an animal - like me - make use of this as a nitrogen source to build proteins? Are there any animals that can do this? Are there ...
2
votes
3answers
644 views

Michaelis-Menten Kinetics: Does measuring apparent Km and Vmax take into account competing reactions?

I am learning about why it is important to measure Km and Vmax for each experimental setup because measuring the "apparent" Km and Vmax includes enzyme inhibitions of which one might not be aware. ...
3
votes
0answers
51 views

What are polytene bands, and why are they there?

Drosophila polytene chromosomes have been particularly useful in genetic research, as it made cytogenetic gene mapping possible with very little effort. This was primarily accomplished due to polytene ...
25
votes
2answers
5k views

What is the advantage of circular DNA in bacteria?

From what I understand, bacteria have circular DNA. What advantages does it have over linear strands like for eukaryotes? Do there exist bacteria with more than one ring of DNA?
1
vote
0answers
41 views

What's the mechanism of action of Levomepromazine's analgesic effects?

I have absolutely no idea as to how Levomepromazine elicits its analgesic effects so please do direct me to journal articles and other credible sources with you, the answerer, making a summary of ...
2
votes
2answers
360 views

What would it take to recognize a deer by its photo?

I am trying to recognize a deer by its antlers or any other means. Elaborating: I was hoping to use their antlers to recognize them but I have heard that most deers shed their antlers every year so ...
1
vote
0answers
63 views

Carrying or packaging capacity of SAD B19 dG rabies virus

I'm wondering about the carrying capacity also referred to packaging capacity or loading capacity (how many base pairs can be packed efficiently into virions) of the pseudotyped rabies virus SAD-dG as ...
2
votes
0answers
94 views

How long does Lentivirus take to express in vivo mouse neurons?

Does anyone know how long it takes for a standard Lentivirus vector to express its genes (under a strong promoter such as CAG, CB7, etc.), after injection into the brain of a mouse? By hearsay I ...
2
votes
1answer
89 views

Confusion related to a term probe-by-background interaction

I was reading a paper related to bioinformatics where it uses the drug response on the cancer cells and the gene expression of the individual cells are studied to find any useful insights. Specially, ...
0
votes
0answers
66 views

Which receptor in particular does, “MUSCARINIC CHOLINERGIC” refer to in Goodman and Gilman?

On pg. 410 of Goodman and Gilman's The Pharmacological Basis of Therapeutics 12th Edition the term "MUSCARINIC CHOLINERGIC" is used (in the context of side effects of antidepressant agents) with ...
1
vote
1answer
114 views

Lineage selection in plasmid evolution

I've been reading through Paulsson (2002) and I am not sure what he means by "lineage selection" in the second to last section. The paper deals with plasmid replication, and mostly concentrates on the ...
2
votes
0answers
197 views

Software for counting fly eggs

Is there any software that could be used to rapidly (quicker than humans) count the eggs laid by Drosophila on a substrate by placing them under a microscope with a camera attached? The eggs are laid ...
10
votes
3answers
643 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
1answer
69 views

Whence fecal E. coli (et al.) if swallowing it is dangerous?

I don't know much about medicine, and I know even less about microbiology, but I understand that there are organisms in the lower gastrointestinal tract (and in feces) of a human, like Escherichia ...
12
votes
3answers
157 views

How are long time periods measured in biological systems?

Biological systems are pretty good at measuring fairly long times, for example, menstrual cycles (month), or puberty (years). Counting days or years seems to be implausible, and chemical concentration ...
1
vote
0answers
22 views

Do the antlers re-grow in the same pattern every year? [duplicate]

I am a software engineer and I am trying to develop a system to identify a deer by its photograph. Most deers lose their antlers every year. I would like to know if they re-grow in the same pattern ...
2
votes
0answers
30 views

How is the appropriately-stratified gut microbiome acquired in organisms performing horizontal transmission?

I am studying horizontal transmission of primary symbionts in insect reproduction. This reminded me of an earlier question I had asked, in which I learned that humans analogously acquired their ...
8
votes
2answers
236 views

What is the smallest molecule that can present as an antigen to the immune system in the context of allergies?

People often claim, in a colloquial sense, that they are "allergic to everything". Is it possible to have a full-fledged IgE mediated allergic response to very small molecules? I was always under ...
0
votes
1answer
116 views

How to classify equilibrium points [closed]

I have the two differential equations: $$\frac{dN_1}{dt} = N_1(2 - N_1 - 2N_2)$$ $$\frac{dN_2}{dt} = N_2(3 - N_2 - 3N_1).$$ I worked out the equilibrium points to be at $N_1 = 0, \frac{4}{5}$ and ...
3
votes
1answer
159 views

What molecular processes are involved in pseudopodial extension?

I am curious as to the processes and mechanisms involved in the extension of pseudopodia in amoeba. How does the cell know and control the direction and extent of pseudopodia formation at a molecular ...
6
votes
1answer
80 views

What are the biological mechanisms behind the increase in cancer risk and alcohol consumption?

Alcohol consumption is known to be a risk factor for developing cancer. Compared to obvious causes like tobacco where one is exposed to known carcinogens, I don't see an obvious mechanism by which ...
-4
votes
1answer
100 views

Were any brain fusion experiments ever conducted? [closed]

Did anybody ever conduct experiments on fusing living brains?
1
vote
1answer
89 views

Reproductive isolation causing evolution

My course book says about reproductive isolation that it does not allow the interbreeding among the individuals of different species. It also says that it is a cause of evolution. How is this cause ...
3
votes
2answers
141 views

What is a bacterial biofilm?

Bacteria produce something called a biofilm. I have found a few definitions; some say it is a complex of live and dead bacteria and others say it is a layer on cell wall. What is it made of? What ...
2
votes
1answer
475 views

Manipulation of gene expression using VP16 fusion and engrailed fusion to a transcription factor?

Today, a presenter briefly mentioned that gene expression in sea urchins during development might be manipulated using VP16 and engrailed fusions. On a slide, it said that expression might be ...
6
votes
4answers
452 views

Chromosomes are of different size but why do all chromosomes have similar GC percentage?

When I browsed NCBI I saw a pattern: even if the chromosome sizes, number of genes, and number of proteins are different, GC% in chromosomes tend to be similar. The examples are linked below. Yeast, ...
1
vote
0answers
147 views

How does Tianeptine work to elicit its therapeutic effects?

Tianeptine is an antidepressant and anxiolytic that has some additional analgesic properties that's used in some European countries, and the theories I've heard about how it works include the ...
10
votes
2answers
357 views

Below which temperature human muscles don't work?

When one exposes theirs body parts to cold environment (especially foot and hands), they may be numb, with temporarily blocked both muscles. What is typical body temperature below which human muscles ...

15 30 50 per page