18
votes
2answers
2k views

Which organism has the smallest genome length?

Which animal/plant/anything has smallest length genome?
18
votes
6answers
838 views

How is evolution possible in contemporary humans?

I would like to know if evolution is continuing to happen in modern humans, assuming things like existence of the nuclear family structure, fidelity to one partner, etc. It seems to me the answer ...
18
votes
4answers
8k views

Can humans eat grass?

Can a human eat grass and digest it? Could it be possible to use it as food just like other plants such as wheat or beans?
18
votes
2answers
2k views

Can rats pass on memories of a maze to their offspring?

A friend of mine told me once about a documentary movie he saw some years ago. On this movie he saw scientists talking about particular experiment. This experiment involved rats and probably ...
18
votes
3answers
1k views

How and where, in the human brain, are memories stored?

Background I am a computer programmer who is fascinated by artificial intelligence and artificial neural networks, and I am becoming more curious about how biological neural networks work. Context ...
18
votes
4answers
1k views

Why do we need red blood cells?

From what I know, the main function of red blood cells is hemoglobin transport. So, why do we need cells packed with hemoglobin: why can't it travel freely in the bloodstream? My own thoughts were: ...
18
votes
1answer
1k views

Is kissing a natural human activity?

The word natural here is meant in contrast to it being a sociological construct. Is kissing in all its forms something natural for humans? Is it instinctively erotic? Or is it just a conventional ...
18
votes
2answers
3k views

Do gene expression levels necessarily correspond to levels of protein activation?

I have seen a lot of research into molecular mechanisms of diseases/phenotypes use measures of RNA as a 'proxy' for the level of protein available in the cell. Is this actually valid? My problem ...
18
votes
3answers
269 views

How crowded is the bacterial cell?

I was wondering what is the protein concentration in an E. coli cell. When studying enzyme kinetics and activity in vitro, I would argue that the substrate and enzyme concentrations resemble those in ...
18
votes
2answers
337 views

Can an adult without genetic lactase persistence still develop a tolerance for dairy foods?

While investigating the rise of adult lactose tolerance, I came across the news that China has been encouraging its citizens to drink more milk, even though most of the Asian population lacks the SNP ...
18
votes
4answers
3k views

Why are there exactly four nucleobases in DNA?

Does someone know why DNA is composed of four nucleobases? In particular, is there an explanation for the number? Why four and not two, or eight?
18
votes
1answer
247 views

Is there any convincing evidence for the existence of nanobacteria?

The existence of nanometer scale microorganisms has been proposed and used explain several phenomena including morphological structures in a martian meteorite (ALH 84001) and implication in the ...
18
votes
1answer
587 views

Do trees age on a microscopic level?

Most animals age via at least two mechinisms: at a "macroscopic" level, basically wear and tear to the point where (on evolutionary time scales) it's more genetically advantageous to optimize for ...
18
votes
1answer
20k views

Why is coffee a laxative?

How does caffeine (or any additional agents) act as a laxative when ingested? I'm interested in the metabolic/signaling pathway.
18
votes
1answer
17k views

What is the difference between HPLC and FPLC and why is FPLC preferable for protein purification?

I've used HPLC (high performance liquid chromatography) before (once, so I'm barely even qualified to know what it stands for) so I was surprised when my labmate told me she would be using an ...
18
votes
3answers
1k views

How long can I store extracted RNA?

If I extract RNA from a (leaf tissue) sample using a one-step phenol:chloroform extraction, how long can those samples be stored at -80°C? And how many times can I defrost and refreeze them before ...
18
votes
1answer
481 views

Natural examples of XOR functions at the cellular level

We can often think of cells as a sort of circuit on macromolecules, and can show that they can accurately and robustly implement functions like $\text{MAJ}(x_1,...,x_n)$ (return $1$ if more than half ...
17
votes
4answers
2k views

How to understand influenza strain designations?

What do the strain designations for flu mean? For example avian flu is classified as H5N1, what do the letters H, ...
17
votes
3answers
1k views

How does the immune system “learn” from a vaccine?

According to Wikipedia: A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one ...
17
votes
3answers
39k views

What is the difference between orthologs, paralogs and homologs?

These three terms are often misused in the literature. Many researchers seem to treat them as synonyms. So, what is the definition of each of these terms and how do they differ from one another?
17
votes
2answers
342 views

How does the microbial environment in your gut initiate?

Clearly, a zygote does not harbor any microbes. As it develops, and the alimentary canal tissue is differentiated, I logically assume that there is still no microbial activity in the fetus's gut. I'm ...
17
votes
2answers
272 views

How do fairy rings propagate?

It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, ...
17
votes
2answers
323 views

What are the major evolutionary pressures for Bioluminescence?

What are the major evolutionary pressures for Bioluminescence?
17
votes
3answers
325 views

How is the blood volume of a living organism measured without killing it?

How is the blood-volume of an organism measured without killing it? NOTE: The blood-volume of an organism is defined as the total volume of blood present inside that organism.
17
votes
2answers
4k views

What is the mechanism behind “acquired” alcohol tolerance?

I can understand natural variation in alcohol dehydrogenase (ADH) in a population leading to variation in rate of inebriation (after controlling for other variables -- e.g., mass, food consumption, ...
17
votes
1answer
1k views

Do insects' muscles become stronger with exercise?

I am curious to know if insect muscles become stronger with exercise, because I have seen many insects get tired out, but I have never seen one get stronger. They always seem to become permanently ...
17
votes
3answers
204 views

What is the optimal frame size for protein secondary structure prediction methods?

The whole question is What is the optimal frame size for the second and third generation protein secondary structure prediction methods? Justify your answer. I remember it has something to do ...
17
votes
2answers
320 views

How is menstruation not suicide in the wild?

Watch any wilderness special for more than a few minutes, and you'll notice a familiar pattern: when a predator catches the scent of blood on the wind, the hunt is on. Wounded animals make the best ...
17
votes
1answer
217 views

Are there dextral/sinistral higher animals?

For example, almost every dog I've met in my life (more than 20 subjects) uses their right paw touching one while asking for attention. Can it be used as a criterion for calling them dextral? If not, ...
17
votes
1answer
783 views

ATP cost for gene expression

How would you estimate the number of ATPs required to transcribe, export and translate a single eukariotic protein?
17
votes
1answer
430 views

What is the lowest pressure at which plants can survive?

What is the lowest pressure at which plants can survive? How the plants behave in a Martian-type atmosphere? Is there any plant that can survive such atmosphere? Can a lichen grow at Martian ...
17
votes
1answer
644 views

Can siRNA induce DNA methylation in mammalian cells?

Some years ago Hiroaki Kawasaki and Kazunari Taira published an article called "Induction of DNA methylation and gene silencing by short interfering RNAs in human cells" in Nature: In plants, ...
17
votes
1answer
2k views

Why do we have five fingers?

Humans (and other humanoid mammals) have five fingers in each hand. Curious to know, why five? Wouldn't more fingers be more useful? Is there any evidence that it used to be different and natural ...
16
votes
8answers
8k views

Why have humans evolved much more quickly than other animals?

Humans have, in a relatively short amount of time, evolved from apes on the African plains to upright brainiacs with nukes, computers, and space travel. Meanwhile, a lion is still a lion and a ...
16
votes
3answers
3k views

Were there any flying dinosaurs?

I've seen some articles which came in contradiction with each other. The first article was talking about flying dinosaurs, dinosaurs with feathers and so on. A couple of other articles are talking ...
16
votes
6answers
2k views

Why isn't a virus “alive”?

The recent news about a new supermassive virus being discovered got me thinking. What biological differences between viruses and cellular organisms have made viruses be deemed non-living?
16
votes
3answers
1k views

Do animals exist with an uneven total number of digits?

I recently finished reading Contact by Carl Sagan. In the book they talk about a pattern in the transcendental number like pi or e, and comment that it is found in base 10 or however many fingers the ...
16
votes
2answers
7k views

How do the brain and nerves create electrical pulses?

I have heard that information is sent between the brain and peripheral nerves via electrical pulses or signals, but I don't understand how they create them in the first place.
16
votes
2answers
382 views

Why would diffusion be faster across a non-specialised tissue?

The standard protocol for a person experiencing chest pains is to chew a 300mg aspirin tablet, the argument being that chewing rather than swallowing the tablet results in the aspirin entering the ...
16
votes
4answers
3k views

Height and natural selection in humans?

I watched the documentary "Evolve" recently and in the segment on "size" Scott V. Edwards, Harvard evolutionary biologist mentioned the idea that humans might evolve to be 7' tall in 'hundreds of ...
16
votes
5answers
773 views

Pipetting damage on cells

I'm curious how much damage is potentially inflicted by shear stress by pipetting. I know that with syringes for stem cell injection cause a lot of damage. However, to what extend does this happen ...
16
votes
3answers
916 views

Are single-celled organisms capable of learning?

I've read that the amoeba is capable of learning. Since these protists have no nervous system, it's safe to assume that even highly simplified learning mechanisms of the Aplysia are miles off in the ...
16
votes
3answers
2k views

Is there any use of CO₂ in human body?

We all know CO₂ as a waste product of metabolism . Does CO₂ have any helpful role , apart from having a role in pH of blood ?
16
votes
3answers
421 views

Are human fetuses more likely to be male? [duplicate]

Question: From a physiological point of view, when sex is determined in a human fetus, is it equally likely to be male or female? Studies in this area typically measure age at birth, where the data ...
16
votes
2answers
4k views

How many humans have been in my lineage? Is it almost the same for every human currently living?

If I were to count my father, my grandfather, my great-grandfather, and so on up till, say chimps, or the most common ancestor, or whatever that suits the more accurate answer, how many humans would ...
16
votes
3answers
5k 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 ...
16
votes
2answers
236 views

Why is there now only one Salmonella species?

Once upon a time, I chanced upon an old microbiology book that detailed the rather colorful world of enterobacteria. Salmonella in particular stood out, as it seemed there were a lot of species: typhi ...
16
votes
1answer
754 views

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle? I originally thought that Krebs cycle was aerobic metabolism ...
16
votes
2answers
1k views

Why is 'Grudger' an evolutionary stable strategy?

I am currently reading 'The Selfish Gene' by Richard Dawkins, which I am sure many here have read. The topic are evolutionary stable strategies (ESS) regarding cooperation. I apologise for the long ...
16
votes
3answers
245 views

What is the reason behind choosing the reporter gene when experimenting on your gene of interest?

I noticed within example experiments in class that different reporter genes are chosen to be inserted near your gene of interest to prove whether or not the gene is being expressed. For example, you ...

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