1
vote
0answers
91 views

Why does trans fat decrease hdl's? [closed]

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
71 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
698 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
30 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
602 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
6k 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
232 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
98 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
342 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
133 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
72 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
314 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
132 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 ...
16
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
116 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
55 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
181 views

Why do marine animals have fins?

Why do Marine animals have fins.
6
votes
3answers
381 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
55 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
355 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?
4
votes
1answer
225 views

Is DNA green viewer carcinogenic?

I use DNA green viewer in Lab to see DNA and RNA bands. Some peers told me it is carcinogenic and is not safe. Is this correct? If yes, are there better choices to use in working with gel?
11
votes
3answers
3k views

Why do red blood cells contain haemoglobin and not myoglobin?

So I am reading about muscles and I come across myoglobin. It has a much higher affinity for oxygen than haemoglobin. So why have animals evolved to have haemoglobin in red blood cells, rather than ...
6
votes
1answer
154 views

Are all chromosomes equally susceptible to mutation?

The humans have been around for a few million years, other organisms longer yet. Changes that occur in the genome and propagate (may) eventually throw a new species ... or atleast branch off the old ...
5
votes
1answer
670 views

What is the fiber axis in the Watson and Crick paper?

I was reading Watson and Crick's article on DNA structure, and the diagram on the lower left of the first page had something called the fiber axis going through the DNA. This axis isn't in modern ...
2
votes
1answer
134 views

How to determine the direction of regulation of a gene by comparing gene expressions?

I am just learning about the gene expressions and regulation. Several researches focus on finding the genes of altered gene expressions on a microarray to claim that they have a correlation to a ...
13
votes
4answers
2k views

Why is the Hydra Biologically Immortal?

I have heard that the Hydra organism is biologically immortal (later I found that there are more immortal organisms). Now I know that its immortality is related to its telomerase. The thing is that we ...
4
votes
1answer
33 views

Effect of Ethanol on Brain Volume Measurements

I want to compare the brain sizes of two populations of fish. However, all the samples I have were fixed in 95% ethanol. As far as I know, 4% formalin is the normal fixative for soft tissues. Can I ...
1
vote
1answer
323 views

How does toluene inhalation damage the brain?

We just had a discussion about toluene abuse. It is known, that people inhaling toluene for a long time have significant brain damage, including decreased intelligence. I found that toluene is a ...
1
vote
2answers
158 views

Why can silicone reduce keloid?

I heard people use silicone sheet for reducing raised scars (i.e., keloids). I was wondering what is the rational behind it, and whether it actually works.
4
votes
1answer
288 views

Why do humans alone have the capability to have religious/spiritual experiences?

What is it in our brain that makes having such experiences possible? I assume other species don't have these. Sure there are instances in the natural world where you can see individuals of the species ...
2
votes
1answer
1k views

Why does yawning impair hearing?

When I yawn I can't hear anything happening around me. I also feel some kind of muscles inside my head contract and hear a faint hum, but it is not loud enough to explain not hearing other sounds. I ...
2
votes
4answers
791 views

Refutation of Darwin's Random Evolution Theory [closed]

I saw this refutation online of Darwin's Random Evolution Theory and cannot see any holes with the logic. Can anyone crack this simple refutation? Refutation of the Theory of Random Evolution ...
2
votes
1answer
145 views

Is this an Emperor Penguin or a King Penguin?

I have a book from Dorling Kindersley called Animal Encyclopedia (the German version that I have is called Das große Tierlexikon) with images from animals. One is titled Emperor Penguin ...
2
votes
1answer
2k views

Which blood vessel carries the most impure blood?

There is a question in my Biology textbook: "Which blood vessel in the human body carries most impure blood after few hours of meal." The answer is given as Renal artery. But I think the ...
6
votes
1answer
303 views

Has any large-scale origin-of-life simulation/experiment been done?

I have been thinking a little about the origins of life, and was further inspired by this question: How did the first self replicating organism come into existence? I can accept that we don't quite ...
2
votes
1answer
428 views

What is the surface area of the human heart?

I heard that the human heart had a surface area of 1000 square feet, and I thought that that cannot be true. So what is the surface area of the human heart and what are the different ways it can be ...
6
votes
3answers
4k views

Why does having cold hands hurt?

(1). Why does having cold hands create a painful sensation? Is it a physical effect, maybe a protection mechanism from evolution? (2). Why, if one's hands are cold, does it feel as if they are more ...
3
votes
0answers
91 views

What are the physiological effects of wine?

I have read that alcohol in general and wine in particular can have advantageous as well as detrimental effects on human health. Is this true? What are the physiological effects of consuming wine in ...
0
votes
2answers
90 views

How might one determine if bacteria are nitrogen fixing or not?

If you had an isolate bacteria sample how would you determine if they were nitrogen fixing?
3
votes
0answers
32 views

What Effect Does the Endocannabinoid System have on Monoaminergic Neurotransmission?

I know that Δ9-tetrahydrocannabinol and other cannabinoids increase dopaminergic neurotransmission in the nucleus accumbens and that this is what results in the euphoria experienced by cannabis users. ...
3
votes
2answers
104 views

Connect the inner and outer space of cell with a wire, will there be electricity?

There is a potential difference, but ions can not go through wires, right? Though there is a electric field, but there is no electron source, I am thinking the answer is no, or will there be some ...
1
vote
0answers
74 views

Are there any mammals in which polyspermy produces viable zygotes?

Are there any mammals in which polyspermy produces viable zygotes? In the wikipedia page it is mentioned that there is a delicate equilibrium between female defenses against many sperms, which ...
2
votes
1answer
44 views

What's the simplest set-up to demonstrate soiless plant growth to middle school students?

I'm looking for a simple, inexpensive way to demonstrate that soil is not needed for plant growth to middle school students. I plan to germinate bean seeds in cotton, but where do I take it from ...
1
vote
0answers
119 views

Cause of secondary symptoms of common cold [closed]

this year I was lucky to get sick by cold twice. First one had as a secondary symptom toothache. The second one was even more interesting in the fact, that when I cough I will fill ache in my ...
3
votes
2answers
1k views

Do neurons secrete multiple neurotransmitters, or just one type?

I know that neurons communicate between each other by filling the junction between dendrites with neurotransmitters. What interests me is if a single neuron only works with one type of ...
3
votes
1answer
127 views

Where does all the food go?

Food goes in, excrements come out. This seems obvious. But it seems like the mass of the excrements is less than the one of the food. Most people I asked answered: "There's a difference because it's ...
2
votes
2answers
101 views

Are humans still competing in the same way now that the first life forms did?

I'm not sure if this is actually a philosophical question, but I was reading a timeline of life on earth and I came to this: 4500-3500 Ma The earliest life appears, possibly at Alkaline vents ...
3
votes
0answers
81 views

Papers linking telomeres and aging [closed]

I'm currently writing a piece of work about telomeres and aging, and wondered if you could share some good papers you've either read or know of.
12
votes
1answer
544 views

Why do we feel tired if we sleep excessively?

When we eat, finally we feel full. I know which mechanism causes the sensation of being full. But when we sleep excessively we often still want more sleep. Why does this happen? Is there a mechanism ...

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