5
votes
2answers
469 views

How are the gene sequences of individual sperm and egg cells “randomized”?

What I mean by "randomized" is, in the place where an egg cell or sperm cell is made, what is the mechanism by which each one is not made identically? Though I am a layman, I'm pretty sure that if the ...
7
votes
2answers
545 views

Did human hairs actually evolve from scales?

What is the evolution of hairs? Did they evolve from scales?
9
votes
1answer
272 views

Can Naegleria fowleri enter through wounds into the bloodstream?

All the sources I've read said that Naegleria fowleri enters the brain through the nose. But lets say that someone had cuts on their arm or leg and they are swimming in water that is conducive to ...
9
votes
2answers
1k views

What is Peter's rule in neuroscience?

I have heard and read about Peter's rule informally in the past, but never saw a formal definition or description. Informally I have learned to understand Peter's rule as the assumed correlation ...
2
votes
1answer
100 views

How do I change bond colors to something besides a different hue in Coot?

I can modify the colors of carbons in Coot under Edit, Bond Colours..., but that only gives me different hues. Is there a way to change the color to something less-saturated (or perhaps slightly ...
11
votes
2answers
27k views

NADH vs. NADPH: Where is each one used and why that instead of the other?

I know NADH is used in cellular respiration and NADPH is used in photosynthesis. What difference does the phosphate group make that the same one isn't or can't be used for both? Is there a greater ...
5
votes
1answer
956 views

How does the enzyme ATP Synthase use a proton concentration gradient to make ATP?

I understand what the enzyme ATP synthase does, but I'm not exactly sure how it does it. I've heard that it uses rotary catalysis, but how exactly does this work? How is the energy from the H+ ion ...
8
votes
1answer
2k views

How does the NAD+/NADH ratio affect lifespan in vertebrates?

Here's the proximate physical implication of the ratio (from the Wikipedia article on NADH). The balance between the oxidized and reduced forms of nicotinamide adenine dinucleotide is called the ...
10
votes
1answer
206 views

How do you design a drug to be delivered to the CNS?

I have just started reading up on structure-based methods for drug design (this is completely not my field so apologies for stupid questions that will be coming along!) Clearly, some drugs are ...
5
votes
1answer
232 views

What is the benefit for cells having the ATP production regulated in mitochondria compared to being from the nucleus?

Mitochondria have their own DNA and appear to be loosely connected to the nucleus and it role. Why are the functions of mitochondria not in the nucleus? Why doesn't the nucleus control the ...
12
votes
1answer
344 views

Looking for a cancer drug target database to guide sequencing of patient tumor DNA

I have a question I would like to pose to the community. I have recently received access to a bench-top ion torrent DNA sequencer. Our idea is to use this machine to sequence the DNA from patient’s ...
9
votes
2answers
394 views

Do mitochondria simply automatically convert glucose to ATP?

I wonder whether there is any intelligent decision-making in mitochondria in the timing of their operation. Do they simply begin ATP production as soon as the correct reactants are present? Or, ...
10
votes
2answers
333 views

Could an “overactive” brain increase the chances of Alzheimer's Disease?

From Raichle ME. 2010. Two views of brain function. Trends in cognitive sciences 14: 180–90: Alzheimer’s disease (AD) is the most common cause of progressive cognitive decline and dementia in ...
9
votes
3answers
1k views

Where is the line between Anaerobic and Aerobic?

I am well aware of traditional anaerobic respiration (lactic acid or alcohol produced - no Krebs cycle) and traditional aerobic respiration (O2 is used at the end of the Citric acid cycle). I am ...
11
votes
2answers
410 views

When did vision evolve for the first time?

Today I wondered what the first organism to evolve vision would have been. I assume that it would have been kind of primitive and basic, but of course extremely innovative and eventually useful to a ...
7
votes
2answers
119 views

Is it possible to trace of the ancestry of a person by only using his/her genetic information?

Is it possible to trace the descent of a person only using his/her genome sequence?
14
votes
2answers
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 ...
14
votes
3answers
365 views

Are human fetuses more likely to be male?

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 ...
12
votes
9answers
7k 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 ...
13
votes
2answers
605 views

How Do Galls Form?

I am curious how Gall Wasps, bacteria and other organisms induce galls to form. Specifically, what chemicals induce gall formation?
13
votes
4answers
943 views

Are there any examples of sudden leaps in evolution?

As far as I understand, various abilities like flying, sight, hearing etc. were caused by slow evolution, where those with a greater ability to to these things had better chance of survival. (If this ...
7
votes
1answer
405 views

How is the effective dose calculated when only part of the body is irradiated?

For calculating the effective radiation dose in Sv, the equivalent dose absorbed by each body part is averaged according to tissue-specific weighting factors, which sum up to 1. If not the whole body ...
10
votes
2answers
3k 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 ...
12
votes
1answer
340 views

Is it correct that the body only responds to the most painful stimulus?

I'm rather ashamed to say that this question is partly based on an episode of House. I have previously heard that, if there are multiple simultaneous painful stimuli, the mind will only feel the ...
25
votes
2answers
496 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 ...
7
votes
1answer
96 views

Which brain regions are D1 dopamine receptors expressed, and which brain regions are D2 dopamine receptors expressed?

This is a follow-up question to If D1 receptors stimulate adenylate cyclase (through GPCRs) and D2 receptors inhibit it, then why do mutations in both have similar effects?. As a further question - ...
5
votes
1answer
145 views

Does AMP/ATP ratio affect lifespan in vertebrates?

The reference below says that a higher AMP/ATP ratio is associated with lower lifespan in C. elegans. Is this finding also generalizable to vertebrates as well? Reference: Apfeld, J., O’Connor, ...
9
votes
3answers
195 views

Does current evidence support the use of resveratrol as an anti-ageing drug?

A while back there was a lot of noise about resveratrol, a naturally occurring phenol which was touted as a potential anti-aging drug due to its role in regulating the SIRT 1 gene. A number of studies ...
6
votes
1answer
65 views

How are chromatids correctly segregated during mitosis?

In my book this is described as happening by kinetochores depolymerising from their attached microtubule spindle, then being dragged towards the spindle's centrosome by a dynein protein. I can ...
2
votes
1answer
79 views

Is the protein in teardrops still attached to cells, or is it released and free-flowing?

A ScienceDaily article says that the protein in teardrops can kill bacteria. But how does it reach the bacteria?
10
votes
1answer
483 views

How do I get the current “camera position” in PyMol so I can reuse it in scripts?

I have a few protein models I want to take pictures of with various ligands bound. It would be nice if I could do it from the same "position", but the only way I can figure out to repeat the same ...
1
vote
1answer
1k views

How do dopamine agonists like amphetamine/methylphenidate affect acetylcholine signalling?

Do they increase it, or is the effect mostly neutral?
4
votes
0answers
105 views

If D1 receptors stimulate adenylate cyclase (through GPCRs) and D2 receptors inhibit it, then why do mutations in both have similar effects?

D1 and D2 both refer to specific types of dopamine receptors. I'm sure it has something to do with the fact that the D1 receptors are in regions different from D2 receptors. I know that adenylate ...
7
votes
2answers
246 views

How many human proteins are very well characterized?

Following up on How many human proteins have a solved 3D structure?,is there a list of very well characterized human proteins / protein complexes? My criteria for "very well characterized" ...
9
votes
2answers
2k views

How is eye color in humans inherited?

In high school we studied the inheritance of eye color, as it was explained to us in the most simple way: blue eye color is a recessive, monogenic, autosomal trait. Now I know that it is a bit more ...
5
votes
2answers
226 views

When does oxidation destroy prions?

It seems like a no-brainer than oxidation, playing the, er, role it does in the universe, would destroy prions just like it destroys everything else. But when does it do that? I assume this has been ...
11
votes
1answer
273 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 ...
9
votes
1answer
167 views

Do taller people have larger somatosensory cortices than short people?

Do taller people have larger somatosensory cortices than short people? What about larger motor cortices? And if so, could this imply that they have less space devoted to other functions, like ...
0
votes
1answer
8k views

How reversible is decerebrate posturing caused by brain stem damage?

This is a follow-up question to How likely would Abraham Lincoln be to survive his wounds today? You don't have to see a CT scan or autopsy to know if the brainstem is injured (directly or ...
22
votes
4answers
8k 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 ...
5
votes
1answer
1k views

Transcription and translation of prokaryotic operons

I'm taking a molecular genetics course, and we're currently discussing prokaryotic operons. The lacZ operon came up frequently for me as an undergraduate as an example for teaching regulatory control ...
11
votes
1answer
496 views

Did researchers evolve multicellular yeast or did they just turn on multicellularity?

In this new paper "Experimental evolution of multicellularity" found via Ars Technica the researchers describe having developed multicellularity and apoptosis within 60 days from a unicellular yeast ...
11
votes
2answers
469 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 ...
6
votes
1answer
178 views

What is the origin of “melting” in molecular genetics?

I'm reading some papers about prokaryotic transcription mechanisms, and I've come across a term I haven't heard before: DNA melting or promoter melting. After reading a bit, it's pretty clear that ...
21
votes
2answers
8k 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 ...
12
votes
2answers
351 views

Are there any plants that fix their own nitrogen?

I know that most nitrogen is fixed through industrial processes and bacterial symbiotic relationships. However, are there any plants that can fix their own atmospheric nitrogen?
10
votes
2answers
211 views

Overlapping genetic information in eukaryotes

In my research, I look at a lot of gene predictions / annotations. Frequently, I see loci where multiple gene models overlap. I haven't taken a systematic approach to analyzing these cases, but I do ...
13
votes
2answers
3k 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 ...
9
votes
1answer
89 views

Which patterns do I have to avoid when modifying the 3'-UTR?

I want to change a pre-miRNA sequence (in my case the pre-miRNA is encoding in a 3'UTR of a gene) and then put it in a lentivirus to see if it is still processed. After modification (permutation of ...
13
votes
1answer
189 views

What is the prehistory of amino acids in cells?

As a followup to Why 20 amino acids instead of 64? and What is the smallest number of amino acids required for life?, I am trying to understand the prehistory of amino acids in cells. All living ...

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