28
votes
2answers
6k 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?
28
votes
3answers
4k views

What actually happens when my leg 'falls asleep'?

Most people have experienced the temporary loss of feeling and tingling in their leg resulting from sitting in an abnormal position for a short while. Usually you get a loss of feeling in your leg ...
27
votes
7answers
472 views

Has there been any observation of species adapting the evolution process?

I am very interested in the evolution of the evolution process itself. There are of course a lot of things that influence how evolution will work, but for this question, I am interested in things that ...
27
votes
3answers
4k views

Do trees really get a large share of their mass from the carbon in the air?

I remember hearing that trees and other plants actually obtain a large amount of their mass from the carbon floating in the air, not the ground beneath them. Does the makeup of air actually contain ...
27
votes
2answers
5k views

What do ants do with our finger nails?

There is place in my house where I cut my nails. Here, there is an ant hole where an ant colony is seen. Whenever I cut my nails from here, they take my nails inside their hole. I was wondering what ...
27
votes
2answers
696 views

What are the trajectories of flying insects?

Many flying insects tend to have very jagged trajectories. For moves of a fruit fly looks like a random walk. Is there any research on the properties of trajectories (e.g. their fractal dimension or ...
27
votes
1answer
1k views

How long will a vegetable live for after being harvested?

I understand this might depend on the types of vegetables, but is there an average or studied specifics? Does it die immediately? Is there a way to precisely diagnose death in plants? If so, what are ...
27
votes
3answers
472 views

Is telomere length a reliable measure of health/lifespan?

Several companies are commercializing tests for telomere length such as this one here. I understand the basic mechanism for why telomeres shorten during DNA replication, but how good is the evidence ...
27
votes
1answer
1k views

Ripening bananas artificially: What is the biological reason

I am a resident of the tropical island of Sri Lanka, and we have a strange traditional method to ripen our bananas quickly. What we do is this: We dig a pit in earth that is enough to put the whole ...
26
votes
3answers
6k views

Why draw blood from veins rather than arteries?

Why draw blood from veins rather than arteries? Is it more convenient or safer?
26
votes
6answers
5k views

How should I ship plasmids?

I shipped 10 µL of my vector miniprep to a collaborator in a 1.5 mL eppendorf parafilmed shut and stuffed into a 50 mL conical with some paper-towel padding. However, something happened on the way ...
26
votes
1answer
3k views

Is humans' height ideal?

More or less we humans are around 1.70 meters tall. My question is, would it be possible to scale us? that is, is it in principle possible having humans 1 cm tall, or 10 meters tall or is there some ...
26
votes
1answer
2k views

Why do ants live so long?

I was surprised to learn that worker ants in some species live many years. I would have expected a lifespan of a few weeks or months (which is apparently the case for many species). What factors ...
26
votes
2answers
415 views

How do biological communities at deep-ocean hydrothermal vents migrate between vents?

Much interest in the astrobiology community has been generated by the discovery of biological communities populating deep-ocean hydrothermal vents (i.e. "black smokers"). (1) These ecosystems rely on ...
26
votes
3answers
6k views

How long does antibiotic-dosed LB maintain good selection?

Various people in our lab will prepare a liter or so of LB, add kanamycin to 25-37 mg/L for selection, and store it at 4 °C for minipreps or other small cultures (where dosing straight LB with a 1000X ...
26
votes
1answer
16k views

Why do cockroaches flip over when they die?

This question has always mystified me since young. For beetles, I can reason that they flip over because they have a higher centre of gravity causing them to be in unstable equilibrium when they tuck ...
25
votes
5answers
625 views

Are there any substance that are more dangerous at low dose than at higher dose?

It is commonly admitted that The dose makes the poison which means as a person, the more I take a substance, the more risk I take for my health. There is even an indicator called LD50 (see ...
25
votes
2answers
12k views

Where do migratory birds go when it rains?

I was reading a comic from XKCD which inspired me to ask this question: "well, where do they go when it rains?" I know that when it rains you usually don't see any birds flying through the sky. I ...
24
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?
24
votes
2answers
2k views

Why was disease transfer to the Americas one-way?

It is well known that the European colonists brought many infectious diseases to the Americas, and that these had a deadly effect on the native populations, because they had no immunity to them. Were ...
24
votes
3answers
2k views

What limits our healing speed?

Our bodies can repair quite a number of injuries very well. However, it takes time. For larger wounds, complete recovery can last many weeks. Why is this time so long, what is the most important ...
24
votes
4answers
624 views

How are the boundaries of a gene determined?

What statistical processes and methods are used by geneticists/molecular biologists to know where one gene starts and one ends?
24
votes
2answers
576 views

Smallest viable reproducing population

What is the smallest viable reproducing population, such as in a human population. By viable I mean a population which keeps genetic defects low (enough). A very strongly related question: what is ...
24
votes
1answer
690 views

How did viruses come to be?

My question is out of curiosity and got me thinking. How did viruses with the head, tail and tail fibres actually evolve? These viruses look more like machines than biological entities. Are there any ...
24
votes
6answers
8k 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 ...
23
votes
4answers
2k views

How do trees manage to grow equally in all directions?

I was walking down a road with these beautifully huge trees when this question occurred to me. Large trees with many thick branches have to grow equally in all directions, or they would tip over. Is ...
23
votes
7answers
5k views

Is there anything that is completely non-toxic to humans at any dose?

Lately I have seen a number of unrelated "scientific" debates over whether certain substances should be outlawed because they are toxic to humans. My initial, informal reaction is usually to respond ...
23
votes
1answer
3k views

How many mosquitoes would it take to “drain” enough blood to put a person into shock?

I'm just curious, how many mosquito "bites" (mosquitoes which have removed blood from a person) would it take to remove enough blood to put a person into shock? (Putting aside all reasons why it ...
23
votes
3answers
33k views

If the brain has no pain receptors, how come you can get a headache?

I've read many years ago in books, that the brain has no nerves on it, and if someone was touching your brain, you couldn't feel a thing. Just two days before now, I had a very bad migraine, due to a ...
23
votes
2answers
17k views

How does cerebrospinal fluid circulate in the central nervous system?

Cerebrospinal fluid (CSF) is produced in the choroid plexus of the lateral ventricles and in the 4th ventricle of the brain. CSF then circulates through the ventricles of the brain and the ...
22
votes
4answers
10k views

How many genes do we share with our mother?

Somewhere I have read we share more than 99% of our genes with every other other person and 98% of our genes with chimpanzees. What does this mean? Don't we share 50% of our genes with our mother and ...
22
votes
5answers
2k views

Why are there species instead of a continuum of various animals?

As I understand it, various animal traits have to evolve gradually, but what happens to the species that are "neither here nor there"? To put it differently, if a species evolved from another, it did ...
22
votes
3answers
2k views

Hot water and bacteria

I know that it is common to say, "use hot water when washing your hands" or when you've got a cut, "wash your hands with warm water," etc. I was wondering, why is this the case? Since bacteria grow in ...
22
votes
2answers
2k views

Why does an electrical shock freeze up muscles?

Why is it when someone comes into contact with an electrical supply that their body freezes up and is unable to move away from the electrical source? Can someone explain this through a physiological ...
22
votes
4answers
843 views

How many times did endosymbiosis occur?

According to the endosymbiont theory, mitochondria and chloroplasts originated as bacteria which were engulfed by larger cells. How many times is it estimated that this occurred in the past? Are there ...
22
votes
4answers
10k 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?
22
votes
3answers
2k views

Is it necessary to conduct a power analysis before beginning an experiment?

I know that power analysis is the statistically valid way to ensure you use the correct numer of samples or repeats in an experiment. But I have never seen any biologist actually conduct a power ...
22
votes
2answers
12k views

If a human takes antibiotics are all bacteria in the body killed?

From my basic understanding, antibiotics kill living things, bacteria for example. Do the antibiotics consumed by a human-being distinguish between what they kill? Or do they just kill every bacteria ...
22
votes
1answer
4k views

How long do your eyes need to adapt to darkness and reach full contrast?

I heard you should wait some time until your eyes adapt to darkness and are able to see smallest luminosity differences, otherwise you might overlook faint objects in the ocular. Are there any rules ...
22
votes
1answer
3k views

What is it that creates that wonderful smell after a fresh rain?

I've heard that the wonderful smell of a fresh rain is actually chemicals released from the trees and grass and other plants. What is the process that allows these chemicals to be released? What ...
22
votes
2answers
3k views

Do all organisms have to die?

I understand (a little) that there are biological clocks and reason that after a certain amount of time organisms die. I'm wondering if that is something inherent in our DNA or in biology/chemistry in ...
22
votes
1answer
608 views

How, on a physical level, does ATP confer energy?

When ATP is used as the energy currency to make, say, reaction X + Y → Z happen, is what happens on a physical level down at the molecular scale that during the reaction ATP + H2O → ADP + Pi ...
22
votes
2answers
10k views

What causes fingerprints to form and why is the pattern formed unique?

I've found research that suggests that the reason we develop fingerprints is because they aid us with feeling surfaces (Scheibert, et al. 2008) and not to increase friction and help with the gripping ...
22
votes
1answer
381 views

Phagemid display

If I'm using a bacteriophage for phage display and I'm trying to avoid avidity effects by using a helper phage what would be the best way to maintain a large library size while keeping everything ...
22
votes
1answer
576 views

Extremely rare occurence of Heart cancer?

The occurrence of Heart cancer (similar, but not the same as Rhabdomyosarcoma) is extremely rare, about 1 per year according to MayoClinic. The reason for this rarity is explained to be the ...
21
votes
5answers
6k 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. Homo sapiens as a species is only 200,000 years old, which ...
21
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, ...
21
votes
2answers
2k views

Which organism has the smallest genome length?

Which animal/plant/anything has smallest length genome?
21
votes
2answers
786 views

How is temperature sensed?

Can anyone summarize the mechanism by which when an object of a given temperature is placed in contact with, say, the skin on a human fingertip, the average speed of the particles of the object is ...
21
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 ...

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