4
votes
1answer
212 views

What insect is this..?

Can anyone tell me what kind of insect (if it is one) is this...!! Or is it the pupa of some insect? Well I don't think that the whole big thing is the insect itself, it appears to be just a kind of ...
3
votes
1answer
129 views

Dehydration by a tea, coffee, beer etc

For the long time I am trying to find out if the following is truth: They say that some beverages dehydrates. I heard that about tea (sometimes green, sometimes black, sometimes both), coffee, beer ...
3
votes
1answer
2k views

Why are hybrids infertile?

Let's take a quote from Wikipedia about zebroids. Donkeys are closely related to zebras and both animals belong to the horse family. These zebra donkey hybrids are very rare. In South Africa, they ...
3
votes
1answer
3k views

What is the standing genetic variation?

I am reading this review. In the first part, the author introduces Standing Genetic Variation, described as: STANDING GENETIC VARIATION Allelic variation that is currently segregating within a ...
3
votes
2answers
227 views

Which hydroxyl from either the phosphate or the glycerol is taken during synthesis of a phospholipid head?

The oxygen anion in the phosphate group is likely to be bonded with a hydrogen cation and thus forming a hydroxyl. When the phosphate group is condensed with glycerol to make a phospholipid, is the ...
3
votes
2answers
249 views

Short-term Lamarckism in asexual single cell organisms

I was reading through the Karr et al. (2012) whole-cell computational model. One of the things they did was to induce single-gene disruptions in their model. They observed several to be fatal, but: ...
2
votes
2answers
91 views

Why mutations in genes involved in general processes like DNA repair increase the risk of developing specific types of cancer?

For example, mutation in MHS2, which encodes a protein involved in the repair of mismatches that occur during DNA replication, dramatically increases the risk of developing colon cancer. (There are ...
2
votes
2answers
28k views

Teens concerned about impregnation through clothes

Dry Humping, is: dry humping is the process of two people repeatedly moving up and down and back and forth on top of each other fully clothed( or missing various pieces, but the penis must not ...
2
votes
1answer
3k views

How to interpret the breeders equation?

The univariate breeders equation is defined as, $\ R = h^2 s$ where $\ R $ is the response, $\ h^2 $ is the heritability (additive genetic variation), $\ s $ is the selection differential. The ...
2
votes
1answer
91 views

Domains in cell membrane

How is movement of proteins and lipids between different domains of cell membrane prevented? Why is the noncytosolic layer not able to do lateral movements between domains but cytosolic layer is able ...
2
votes
1answer
104 views

Do plant-plant interactions inhibit growth?

Plants produce lots of compounds that inhibit (kill or irritate) microorganisms and insects. They have defenses against plant viruses and infections. What kinds of compounds or hormones to plants ...
1
vote
1answer
102 views

Influence of temperature on protein binding and decay rates

For computer modeling purposes, I am looking for some referenced quantitative measurements of the effect(s) of temperature on the dynamic of biochemical reactions. Question In particular, my ...
1
vote
1answer
71 views

Is there a possibility that medicine will affect the efficiency of natural selection?

I mean, saving sick people means that they possibly can propagate something that nature does not allow. I know that there is already something that operate at genetical level producing alteration, ...
0
votes
1answer
72 views

At what saltiness will water simply pass through us?

If water has a low salt content, it hydrates us. When water has too high salt concentration, like sea water, it drains water out of us instead when we drink it. At what salt concentration would water ...
81
votes
1answer
8k views

Do bacteria die of old age?

I know that the cells of mammals at least stop dividing when they are old, and then die a programmed cell death. Then other cells have to replace them. But in a bacterial colony, each cell ...
94
votes
2answers
3k views

How many times did life emerge from the ocean?

Evolution is often mistakenly depicted as linear in popular culture. One main feature of this depiction in popular culture, but even in science popularisation, is that some ocean-dwelling animal sheds ...
48
votes
2answers
7k views

Do ants or other insects sleep, and if so why?

I was thinking yesterday about insects (as there was a spider in the house, and I couldn't help but think of anything else, even though they aren't insects), and I started to wonder if ants sleep? ...
46
votes
5answers
5k views

Life without DNA?

I'm by no means an expert in the field, merely a curious visitor, but I've been thinking about this and Google isn't of much help. Do we know of any lifeforms that don't have the conventional ...
34
votes
4answers
21k views

Is there any advantage to one blood type over another?

All humans can be grouped into ABO and Rh+/- blood groups (at a minimum). Is there any advantage at all to one group or the other? This article hints that there are some pathogens that display a ...
22
votes
3answers
4k 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 ...
15
votes
3answers
10k views

Supercomputer Vs Human Brain

With supercomputers doing calculation in petaflops ($10^{15}$ Calculations per Second), have we crossed the speed of Human Brain?
33
votes
3answers
7k views

Can humans perceive sounds above 20 kHz?

In the never-ending debate raging in the audiophile community about sound quality and what humans can or cannot hear, it is very very very very incredibly often cited that the upper-limit of the ...
34
votes
1answer
30k views

How does laughing gas (N₂O) work?

Laughing gas (N2O), well, makes people laugh. How does just a gas make us do that, there has to be some hormones at work... So, I wanted to know how this works? What is the mechanism?
23
votes
5answers
12k views

Why do the two hemispheres of the brain control the opposite sides of the body?

Why does the left hemisphere control the right and the right hemisphere control the left? I googled it but didn't find a good answer regarding this. Could someone explain? Does this adaptation help ...
16
votes
4answers
112k 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 ...
16
votes
2answers
1k 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 ...
12
votes
1answer
15k views

Why is ATP the preferred choice for energy carriers?

Why is ATP the most prevalent form of chemical energy storage and utilization in most cells?
9
votes
1answer
332 views

First RNA polymerase-mRNA

We know that RNA polymerase produces mRNA by reading DNA strand. Which enzyme produces the first RNA polymerase if other RNA polymerases are synthesized in the same way like other enzymes(proteins) ?
24
votes
1answer
9k views

What do you see when your eyes are closed?

If you are in pitch black and you close your eyes, you sometimes can see strange shapes of various colors. A lot of the time these shapes and colors change as you observe them. This phenomenon still ...
15
votes
1answer
13k views

What is the female equivalent of the morning erection that some men experience?

There was question about what causes "morning wood." It was answered that the erection in the morning is caused by decline of norepinephrine during REM sleep. Which in part allows to prevent ...
13
votes
3answers
18k views

Do apes and humans share 99% of DNA or 99% of genes? What is the difference?

I made an answer on the Scifi.SE that can be read here. It is about how the characters in the story Jurassic Park might have gotten DNA for all the species shown. In my answer, I said this: Apes ...
12
votes
2answers
296 views

Did Darwin ever reach the conclusion that selection will remove variation?

According to simple models of selection the genetic variance in a population should be reduced by selection. (Fisher's fundamental theorem states that the rate at which a population can evolve is ...
9
votes
2answers
4k views

Does one parent transmit more DNA to the offspring than the other one?

Does one parent transmit more DNA to the offspring than the other one? Or do both parents always transmit the same amount of genetic material to their offspring? In other words, can a baby be ...
7
votes
1answer
923 views

Fisher's Geometric Model for Dummies

Fisher's geometric model is still today one of the most important and fundamental model in evolutionary biology but it seems to me that most student in evolutionary biology don't really understand it ...
6
votes
1answer
3k views

Are sensory receptors neurons?

Background There are many receptor types in the body, with various functions and various mechanisms of transduction. Receptor cells are considered to be part of the peripheral nervous system, as they ...
36
votes
4answers
114k views

What's the maximum and minimum temperature a human can survive?

This is a question that has been in my mind since I was a kid. I'm not a doctor, nor even a biology student, just a curious person. What is the minimum and maximum temperature a human body can stand ...
23
votes
4answers
1k 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 ...
20
votes
3answers
466 views

Good source that explains the evolution of single-celled organisms “from scratch”

Are there any books or sites that detail, step-by-step, the evolution of the first single-celled organisms (bacteria, archaea) from a Miller-Urey-like beginning? That is, assumes only amino acids, ...
14
votes
4answers
3k views

If body temperature is 37°C (98.6°F), why are most people more comfortable at around 21°C (70°F)?

It may be different for other people, but for me, anything above 32°C (90°F) is very uncomfortable, and my body is inclined to seek cooler temperatures. But I would think that at 32°C, the body would ...
14
votes
1answer
3k views

Why does hair turn grey or white, and why does it happen later for some?

The question is pretty simple: what is happening molecularly when hair turns grey or white? I would imagine that it is due to the lack of a particular compound. I'm also interested in why some ...
13
votes
3answers
5k 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 ...
12
votes
3answers
3k views

What does irregular heartbeat mean in simple language?

I bought a blood pressure monitor (A&D UA-851) which has the option to measure irregular heartbeat. I do understand what 'irregular' means, but why do irregular heartbeats happen and what are ...
10
votes
3answers
2k views

Why did humans become bipedal?

Somewhere in evolutionary history homo started walking upright and became bipedal. You hear these hypotheses that, by walking upright, they could see better across the grassy savannas to escape ...
9
votes
2answers
560 views

Do immortal organisms exist?

Do organisms exist that are able to live indefinitely if they are not killed by external factors? Under external factors I would consider things like predators and natural disaster but not illness by ...
8
votes
1answer
3k views

why is DNA antiparallel? Can it be parallel?

My biology textbook mentions that DNA is antiparallel and it got me wondering... Can DNA be parallel? What would happen if it was parallel? could DNA still replicate right?
6
votes
1answer
177 views

The origin of molecular machines

DNA holds genetic information and holds the key to the evolution of living organisms. Transcription and translation mechanisms enable living cells to process information encoded in DNA. To that end, ...
5
votes
1answer
684 views

Is there any size limit to the amount of information a human (or other) brain can hold

Im not sure how this would ever be tested but is there a limit to how much the brain can 'hold' before it reaches capacity ? I guess this could also be interpreted in terms of memory, as how well ...
4
votes
1answer
131 views

What effects does being cryogenically frozen have on a person's body? [closed]

I'm wondering what effects are known to happen to a person's cells when a person is cryogenically frozen, especially those that need to be overcome in order to "bring them back to life." From a ...
3
votes
1answer
154 views

What in neurons and their connections changes during the process of learning?

I'm not sure if this question belongs more in physics or biology (or maybe even computer science)... but biology seemed to fit more. What changes in the state of our brains when we learn things? ...
3
votes
2answers
1k views

What are gram negative and positive bacteria?

I've just finished a course of double antibiotics for Helicobacter pylori in my stomach. I looked up H. pylori and found that it was a gram-negative bacterium. I looked up gram-negative and didn't ...

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