14
votes
1answer
195 views

Paralogous genes in genome-wide association studies?

Has anybody tested if paralogous genes are over-represented among the genes identified by genome-wide association studies (GWAS)? For example, if a GWAS study finds 200 genes associated to the ...
13
votes
5answers
3k views

Do humans have enough biological differences to be grouped into races or subspecies?

After my online research on the subject, I learnt that, biologically speaking, many scientists believe that there is no such thing as a race, because Homo sapiens species is only 200,000 years old, ...
13
votes
4answers
57k views

Why is DNA replication performed in the 5' to 3' direction?

DNA replication goes in the 5' to 3' direction because DNA polymerase acts on the 3'-OH of the existing strand for adding free nucleotides. Is there any biochemical reason why all organisms evolved to ...
13
votes
9answers
5k views

Why didn't the polar bear change its color from white to black during evolution to absorb heat?

Polar bears are white in color and white color is not a good absorbant of heat. Why then didn't they evolve a black color to absorb more heat?
13
votes
5answers
347 views

Can species back-evolve?

One of the tenets of Darwin's theory is the survival of the fittest, ie adaptation of features that allow a species to adapt better to its surrounding environment. I am wondering that given the right ...
13
votes
5answers
4k views

Can any protein be phosphorylated?

I am working with an Arabidopsis mutant with an F-box protein knocked out. It has been shown that F-box proteins targets must first be phosphorylated (Skowrya et al., 1997). I have heard of ...
13
votes
3answers
833 views

What evolutionary explanations are there for death?

I know death and cancer doesn't hurt humans' reproductive success. It's not helping either. Why do we die? Why dying humans (all of us) are common? What's the point of dying?
13
votes
3answers
36k views

What is a coupled reaction and why do cells couple reactions?

I was wondering what exactly a coupled reaction is and why cells couple them. I read the wikipedia article as well as several others, such as life.illinois.edu but I still don't get it. Could ...
13
votes
4answers
31k views

What is the armpit hair for?

Modern human beings, especially women, cut their armpit hair. It seems to me the armpit hair is trivial/useless. Shortly speaking, what is the armpit hair for?
13
votes
3answers
2k views

How does the human body metabolize gasoline?

A Chinese man has been drinking gasoline to relieve his pain for 25 years. How does the human body metabolize gasoline? Also, what are the side-affects to gasoline?
13
votes
3answers
802 views

How many human proteins have a solved 3D structure?

I was wondering how many human proteins have a solved 3D structure. Is there a database with only human proteins? I looked at pdb but couldn't find a filter.
13
votes
3answers
3k views

When has an organism evolved enough to be called a new species?

Imagine that we take a population of horses, split them in half and place them in completely different environments. The two species will evolve separate from each other and because the environment is ...
13
votes
5answers
1k views

Why are some genes dominant over others? What is the mechanism behind it?

If I have a brown eye gene which encodes the protein that is responsible for the brown color and have a blue eye gene as well, what is the reason that my eye color is brown? How does one gene maintain ...
13
votes
2answers
437 views

Are there issues with filling PCR tubes to capacity?

I'm planning to scale up a PCR reaction, and I'm wondering if filling the PCR tubes to the maximum volume of 200 ul would be a problem. It would mean a lot less pipetting as I would only need 1/4 of ...
13
votes
4answers
2k views

Why would a single celled organism evolve to be multi-celled?

I read a story this week on Richard Lenski who has been 'evolving' E. coli for more than 50,000 generations now. One comment I read was from someone who doesn't accept Evolution who pointed out that ...
13
votes
2answers
4k views

How will rising carbon dioxide levels in the troposphere affect photosynthetic producers?

Much discussion has been had about the affects of climate change on plantlife, but how will rising carbon dioxide concentrations affect the photosynthetic process itself? Since CO₂ is a reagent in ...
13
votes
2answers
398 views

Evolution in 37 years, is it possible?

I am confused, can evolution ( speciation ) really occur in such a short time ? In 1971, biologists moved five adult pairs of Italian wall lizards from their home island of Pod Kopiste, in the ...
13
votes
3answers
591 views

Why is there a difference in the rotation of the tail fin in fish compared to marine mammals?

I've been thinking about this one, but I can't seem to find what causes this difference. All fishes that I've seen have their tail fin positioned vertical: But all the marine mammals I know have ...
13
votes
2answers
504 views

Intrinsically disordered proteins as potential drug targets

Intrinsically disordered proteins (IDPs) are a class of proteins that do not adopt a stable secondary or tertiary structure under physiological conditions in vitro, but still have biological ...
13
votes
3answers
1k views

What implications has the missing 2'-OH on the capability of DNA to form 3D structures?

The chemical difference between RNA and DNA is the missing 2'-hydroxyl group in the nucleotides that build DNA. The major effect of that change that I know of is the higher stability of DNA compared ...
13
votes
2answers
7k views

Why do people have antibodies against other blood types?

The ABO blood type divides each blood type according to whether they have the "A" and "B" antigen(s) (AB has both, O has none). People also have antibodies against the antigens they don't have (AB has ...
13
votes
2answers
645 views

Does testosterone increase female sexual behavior?

According to my lecture notes testosterone generally increases sexual behavior. Given that it's generally thought to be the male hormone I'm not quite sure whether they mean that it also increases ...
13
votes
1answer
1k views

Why do we experience temperatures below 37 degrees Celsius as 'hot'? [duplicate]

We always prefer to be in 20-25° C, although our core temperature is about 37°? Why is our skin temperature lower than our core temperature?
13
votes
2answers
3k views

What effect does vortexing have on a fluid sample that simple mechanical shaking does not?

Some protocols call for fluid samples to be mixed with a "vortexer" on the high setting. What effect does the vortexing have on fluid samples that mechanical shaking does not? Does it shear long ...
13
votes
2answers
982 views

Why do we get runny noses in the cold?

The most annoying thing for me about being cold is a runny nose. Is there an advantage to having a runny nose when cold? What does having a runny nose achieve?
13
votes
2answers
258 views

Percentage of genome devoted to regulating gene expression

Recently I've been studying the p53 tumor suppressor gene as a model for regulation of gene expression. It's amazing how many different post-translational modifications are known to regulate p53 ...
13
votes
1answer
3k views

How does a plant grow before photosynthesis is possible?

During photosynthesis, a plant translates CO2, water and light into O2. I assume the carbon C is further used for the growing process. I wonder how the plant grows before the time where photosynthesis ...
13
votes
3answers
3k views

Why can white hairs get dark again?

I have learned (probably in high school?) that hairs turning white is caused by the part of the folicle which produces the pigment dying and being replaced by an air bubble. This sounds very ...
13
votes
2answers
960 views

Is the EC50 of an activating protein for an enzyme a good indicator for the binding affinity Kd?

We work with a membrane protein system where measuring the affinity between the enzyme and the upstream activating protein has been difficult, and when measured in detergent solution, it is almost 100 ...
13
votes
1answer
3k views

Why does Penicillin only affect bacterial cell walls

I was quite fascinated by the feature Should Science Pull the Trigger on Antiviral Drugs—That Can Blast the Common Cold? in this month's Wired magazine. They explain that Penicillin is effective at ...
13
votes
3answers
810 views

Why do restriction enzymes tend to have an even number of bases in their recognition site?

When reading my textbook I noticed that in all examples but one from eight the recognition site was an even number of bases. I wondered if this was just a co-incidence, so I took the data from this ...
13
votes
2answers
559 views

Are there neurons that can sense light shining in your ears?

I know someone who bought earphones that shine light in you ears. According to what he was told, there are neurons that sense light and then make you feel wide awake when activated, which seemed like ...
13
votes
3answers
1k views

Why does hair grow after trimming but remains at a constant length after a while?

Some hair especially body hair regrows after trimming but stops growing after a while. What is the mechanism behind control of hair growth and how is the length limit determined?
13
votes
1answer
903 views

What did Richard Feynman contribute to molecular biology?

Some time ago, I read James Gleick's "Genius: The Life and Science of Richard Feynman", a wonderful biography of Feynman and, by extension, most of modern physics. In this book, the author mentions ...
13
votes
2answers
506 views

Which is more important for protein expression mRNA structure or codon optimization?

The field seems extremely divided on the debate. On one hand, artificial experiments have suggested that synonymous mutations don't correlate with gene expression but rather, the mRNA 5' structure is ...
13
votes
2answers
430 views

What is the morphological difference between Leydig cell in human and pig?

The pig is only an example, just an animal. Leydig cells have protein inclusions (Reinke crystals) that are mostly made of crystallised lipofuscin. They are secretory inclusions i.e. cells formed in ...
13
votes
3answers
300 views

Can plants get cancer?

I can't think of any reason why plants wouldn't be able to get cancer, but I've never heard of a plant growing a tumor. I've also never seen a plant with a noticeable abnormal growth. Can plants get ...
13
votes
2answers
3k views

How many people are required to maintain genetic diversity?

Imagine humans were to colonize a distant planet and it was a single one-way trip. How many people would they need to bring? Obviously 2 is the minimum, but that would result in a lot of inbreeding. ...
13
votes
1answer
942 views

Are human bodies programmed to die?

Following from this question: What is the evolutionary advantage of death?: Is there any evidence that human bodies have systemic self-destruction built into their developmental program? I'm not ...
13
votes
2answers
447 views

Why are there N's after Sanger sequencing?

After sending a DNA sample for sequencing, the resulting sequence had N's in the beginning and end of the sequence. I know the N's mean that the computer can't tell what the base pair is, but why is ...
13
votes
1answer
9k views

What effect has changing pH and salt concentration on protein complexes?

I'm struggling to find peer reviewed literature that explains the effect of changing the pH and the salt concentration on protein/protein complexes in solution. What effect does the pH and the salt ...
13
votes
1answer
386 views

The Origin of Mitochondria

For a long time I've just accepted, because it is just what everyone told me, that mitochondria became organelles in the cell when they were "engulfed" by another cell which acted like it's host. This ...
13
votes
1answer
322 views

How do members of cryptic species know who to mate with?

According to Wikipedia: In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each ...
13
votes
1answer
641 views

How many people's DNA were involved in the compilation of the reference human genome?

I know that the reference human genome is complied from DNA portions from different people, most of whom were European. Do you know how many of them were involved? Do you know which ones were ...
13
votes
2answers
332 views

When does BLAST fail to align 2 DNA sequences?

This is an assignment that had confused me for a long time. So I think you guys who study computational biology might be interested. The original question is: Find the two most similar DNA ...
13
votes
4answers
292 views

Machine learning for light microscopy — problems to solve?

I would like solve some biological problems that would improve the state-of-the-art of biology or bioinformatics. In particular, I want to apply machine learning on light microscopic images. The ...
13
votes
2answers
399 views

What kind of fruit is this?

Just spotted this fruit while walking to school. It's the size of a small coin.The taste is almost sour and tangy and somewhat sweet (I only tried one of them and very little of it). I admit, ...
13
votes
1answer
224 views

How does herpes (HSV) infection suppress HIV?

HIV compromises the human body to defend against infection. Yet people who are infected with herpes are at less risk of developing AIDS. How does this work?
13
votes
2answers
228 views

What is the contribution of viruses to the evolution of mankind?

I'm interested in horizontal gene transfer in bacteria, viruses, and organisms such as Bdelloid Rotifers. I've just read in Carl Zimmer's 'A Planet of Viruses' the following passage: As a host ...
13
votes
1answer
16k views

Are mosquitoes repelled by high frequency sound?

I am totally confused whether ask this question to physics or biology stackexchange. I downloaded a mobile application which claims to repel mosquitoes. This application basically produces sound from ...

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