20
votes
3answers
436 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, ...
19
votes
5answers
6k 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 ...
17
votes
5answers
1k 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 ...
15
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 ...
14
votes
1answer
2k 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
4answers
2k 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 ...
13
votes
3answers
4k 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 ...
11
votes
3answers
762 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
13k 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 ...
9
votes
1answer
6k 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 ...
9
votes
3answers
2k views

Why did abiogenesis only happen once?

If the "primordial soup" theory of abiogenesis is to be believed, self-reproducing organisms spontaneously arose on Earth at least 3.5 billion years ago, surprisingly soon after the Earth cooled down ...
8
votes
2answers
135 views

Why is there no way to remove an immune response?

We've known for a long time now how to "add a new entry to the database," as it were, of immune responses. It's called vaccination, and it's been one of the greatest success stories in the history of ...
7
votes
2answers
209 views

How does Natural Selection shape Genetic Variation?

Background Importance of the additive genetic variance As stated here, the fundamental theorem of Natural Selection (NS) by Fisher says: The rate of increase in the mean fitness of any organism ...
7
votes
2answers
449 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 ...
15
votes
3answers
827 views

Why do some trees have a life span, while some don't?

I have heard that there is no limit on the growth of trees, but then why do some trees, such as boxelders and poplars, tend to live shorter than redwoods, for example? Some advertisements for improved ...
14
votes
2answers
35k views

How many human cells are there in our body, on average?

How many human cells are there in our body, on average? Wikipedia says 1013: Bacterial cells are much smaller than human cells, and there are at least ten times as many bacteria as human cells in ...
10
votes
1answer
259 views

Is it a limitation of the eyes, or the brain, that we can't see a moving bullet?

Are the photoreceptors in our eyes not fast enough to register the fast moving bullet, or is the brain not powerful enough to make sense of something happening that fast?
10
votes
2answers
700 views

Why does strenous exercise cause vision of “lights”?

I had a hard climb a week ago. I got so tired then any time I closed my eyes I saw these lights inside my head. I see these lights almost every time that I run fast or some thing like that. What are ...
9
votes
3answers
6k views

Why can all animals swim in water without learning to swim but humans cannot?

I had a question since I was a child. I was always curious about the fact that all animals can swim in water. They don't need any training or to learn swimming. But humans need to learn to swim. Why ? ...
9
votes
2answers
160 views

What role does a protein's size have on protein-protein interactions?

Protein-protein interactions are when two or more proteins bind together, possibly for some important biological function. Recently, I'm starting to look more into proteins, and in particular, ...
8
votes
1answer
1k views

Does extracted DNA degrade after a certain time period?

For direct use as template in PCR runs. Chelex 100 5-10% w/v extraction. Without listing the whole protocol, in the end the supernate is decanted off and then stored at 4°C. I was under the impression ...
7
votes
2answers
315 views

Why sleep? No, actually, why wake?

I was just reading the sleep threads, and I wondered, why is the body so constructed so that sleep is necessary? (Is it just a design error?) But then, how do things come to be awake at all? How did ...
7
votes
4answers
589 views

Suitable introductory book on Bioinformatics for a computer scientist?

Do you have any suggestions on a suitable introductory text on bioinformatics for a computer scientist? Any recommendations with pros and cons of different books would be appreciated. I'm mainly ...
6
votes
2answers
1k views

Why do DNA and RNA have the functions they have?

I know that there are two most important directions of genetic information transfer in living organisms: DNA->DNA and DNA->RNA. The first is replication, and the second is transcription. I wonder if ...
5
votes
1answer
311 views

What is a Mitochondrial Eve and Y-chromosomal Adam

I've read this question: What kind of event would cause the current Mitochondrial Eve to be replaced by a new one? And the values in Wikipedia about Mitochondrial Eve and Y-chromosomal Adam and I am ...
4
votes
1answer
92 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 ...
4
votes
1answer
539 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
2answers
337 views

How does the brain know where a signal came from? What is the addressing system

I am an electronic engineer so I am thinking about this from an electronics outlook. How does the addressing system work, As I see it, the nervous system is small parallel branches attached to larger ...
4
votes
3answers
1k views

Chromosome 2 fusion?

I read this article by Jeffrey Tomkins and Jerry Bergman claiming to debunk chromosome 2 fusion. Is there anything wrong with these conclusions? " 1.The reputed fusion site is located in a ...
3
votes
1answer
219 views

Elevated position effect on recovery times from upper respiratory infections at rest?

In nursing school, they advice for people with upper respiratory infections to be in a slightly elevated position at the head region when sleeping. My intuition of the reason is that the lymphatic ...
3
votes
1answer
247 views

Ventral stream pathway and architecture proposed by Poggio's group

Please can you give me a very brief explanation about all functions in the ventral stream architecture summarized in this figure: This figure is from Serre et al.'s A quantitative theory of ...
3
votes
2answers
840 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 ...
2
votes
2answers
228 views

Book recommendations for algorithms used in evolutionary biology

Do you have recommendations for a book that presents the different algorithm used in theoretical evolutionary biology? I don't mean evolutionary or genetic algorithms (otherwise this question would ...
20
votes
2answers
852 views

Why is rabies incurable?

I'm still not sure about the mechanics that lead to rabies being incurable. I know that it can be treated before any symptoms show up, but why is it that once symptoms show the person is a dead man ...
18
votes
1answer
240 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
2answers
413 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
2answers
914 views

How do plant galls form?

I am curious how Gall Wasps, bacteria and other organisms induce galls to form. Specifically, what chemicals induce gall formation?
14
votes
4answers
2k views

Can two humans with 44 chromosomes produce viable offspring?

It is known that there are very few individuals having 44 chromosomes, not the usual 46 chromosomes. One example is a male in China: the first article, the second article. The other is a female in ...
14
votes
4answers
74k 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
2answers
661 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 ...
12
votes
1answer
287 views

How fast can a human run?

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly ...
11
votes
2answers
482 views

How sterile is sterile when working with nucleic acids to prevent contamination?

I am reading up on preparatory work on working with nucleic acids and a lot of the instructions speak on excessive procedures on cleaning environments with high %ethanol and making sure the equipment ...
11
votes
2answers
4k views

Do identical twins have the same fingerprint?

When there is every thing same from their genes to their phenotype so then why they don't have same fingerprints?
11
votes
2answers
6k views

Why is a lack of oxygen fatal to cells?

In animals temporary anaerobic respiration leads to the breakdown of the pyruvate formed by glycolysis into lactate. The buildup of lactate in the bloodstream is accompanied by a large number of ...
11
votes
2answers
232 views

Under what conditions do dendritic spines form?

I'm looking for resources or any information about the formation of dendritic spines and synaptogenesis, especially in relation to how new connections are formed on a daily basis. Does the ...
10
votes
2answers
699 views

Do insects with compound eyes have depth perception?

Do insects with compound eyes have depth perception? They fly as if they do, but their eyes are so close together it seems like the image would be 2 dimensional.
8
votes
1answer
6k 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?
8
votes
3answers
417 views

Long-term-potentiation and memory. Where do we stand?

I was reading the answers to the question: How and where, in the human brain, are memories stored? and, as expected, LTP and LTD came out. Every time I read about LTP/LTD there is always something ...
7
votes
2answers
269 views

Why do we have more male infant born?

For every 104 male babies,we have 100 female babies and there is a Statistics which is more reliable (we have 997 female infant born per 1000 male infant born). what's the reason? why do we have male ...
6
votes
1answer
716 views

Why does a light object appear lighter in your peripheral vision when it's dark?

So, I am not sure I can reproduce it via images, but the steps are: 1) At night, open a window and have a look at the surface of the earth 2) Suppose there's an object that reflects a tiny amount of ...

15 30 50 per page