3
votes
3answers
369 views

Sources for common laboratory Saccharomyces strains?

I'm used to working with bacteria - some of the more common laboratory strains sometimes come with an order from some vendors. What's the most convenient source to order common straings of ...
2
votes
2answers
197 views

How to define “evolution”?

The standard answer to the question: what is evolution? is: It is a change in allele frequency over time! I believe a complete definition should encompass the following concepts: ...
17
votes
2answers
4k views

Is there an advantage to linear chromosomes?

The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
13
votes
2answers
4k 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 ...
12
votes
4answers
15k views

What nutrients can humans absorb in the mouth?

For instance, I realise being able to absorb simple sugars in the mouth is pivotal in the rapid action of oral glucose gel. Thus I was wondering what nutrients in general can be absorbed directly ...
12
votes
4answers
364 views

Is there any documented evidence for suicide among vertebrates other than humans?

Is there any documented evidence for suicide among vertebrates other than humans? Lemmings not accepted !
11
votes
1answer
1k views

Could humans and chimpanzees hybridize?

In some cases two species can hybridize. For example, Tigers and lions can hybridize to produce "Ligers". Would it also be possible for humans and chimpanzees (or any other species) to hybridize ? ...
9
votes
2answers
18k views

Why does human facial and head hair continue to grow?

Many people can grow extremely long head hair and facial hair. Are there evolutionary theories as to why this is the case? It seems like having long hair could be a disadvantage, and extremely long ...
8
votes
2answers
290 views

Can forensic DNA analysis be used to generate a visual approximation of a suspect?

In light of the current US supreme court case, I'm curious if enough information can be teased out of a DNA sample to get a "reasonable" approximation of the suspect (never mind the legality). I ...
8
votes
3answers
15k views

Does our DNA change during our lives?

As far as I know, DNA is the construction protocol of all organisms on Earth. Does it change when influenced by time and environment (physical laws)? As parents with schizophrenia are more likely to ...
7
votes
2answers
216 views

Sugar as a defence against bacteria?

An answer on another SE site mentions that sugar "at a certain level acts as a preservative". I've always been taught that microorganisms eat sugar and expel acids, that is why sugary food are ...
7
votes
2answers
233 views

HIV Rapid Tests

The hiv antigens that are used in the oral rapid tests, are they infectious? The tests do not contain any actual virus but I am curious if the antigens themselves could somehow create the virus on ...
7
votes
1answer
308 views

What keeps the resting potential of neurons constant at -70 mV?

I know the sodium-potassium pump pumps out 3 Na+ ions and pumps in 2 K+ ions per reaction so the negative charge in the axon increases. However, once the voltage (difference of charge inside and ...
6
votes
1answer
522 views

Empirical evidence for species selection

Do we have any empirical evidence in favor of species (or lineage) selection? Do we know some cases that can only be explained (or seem to be only explained) by lineage selection? What are today the ...
5
votes
3answers
19k views

Evolutionarily speaking, why do humans have 46 chromosomes

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Monkeys, chimpanzees, and Apes have 24 pairs (twenty-four pairs), for a total of 48. What caused humans to have 46? ...
5
votes
2answers
316 views

How can E. coli proliferate so rapidly?

The E. coli has a genome with approximately 5×106 bp. The main DNA polymerase involved in its chromosome duplication (DNA pol III , the one with highest processivity) can polymerize ~103 nucleotides ...
4
votes
1answer
332 views

Parasitism and mimicry

I was reading this article which states this: Classical Batesian mimicry, in which an undefended mimic evolves to look like a toxic model, is a parasitic relationship in which the mimic gains ...
4
votes
2answers
453 views

Why White Blood Cells (WBCs) do not react to foreign bodies like sperm?

Why do the white blood cells allow foreign bodies like sperm to exist inside body cavity without any reaction? White blood cells function is to fight against foreign bodies (from the text books).
4
votes
1answer
145 views

If the average resting potential of a neuron is -70 mV, why is there such a high ratio of potassium ions inside relative to out?

My bio teacher was discussing the ratios of different ions inside versus outside the cell. $$\text{OUT:IN}$$ $$\text{K}^+ (1:20)$$ $$\text{Cl}^- (11.5:1)$$ $$\text{Ca}^{2+} (10000:1)$$ $$\text{Na}^+...
3
votes
2answers
241 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
253 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: ...
3
votes
2answers
5k views

Is there a difference between polarity and hydrophobicity?

From literature the two terms seem to be interchangeable when discussing protein domains and motifs. But biochemically, what are the specific differences between these two terms? For example what is ...
2
votes
2answers
93 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 ...
1
vote
1answer
104 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
97 views

Is it possible to have multiple stop codons in one exon?

I would be very happy if someone can help me to find the answers for the following related questions. Can one exon have many stop codons? Can protein synthesis happen, if the stop codon is at the ...
0
votes
1answer
73 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 ...
0
votes
2answers
10k views

Will I grow taller? How can i tell? [closed]

I'm 17 and I'm about 160 cm and my weight is 47 kg . I just want to know if I will still grow taller ?
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 ...
99
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 ...
54
votes
3answers
12k views

How does the brain's energy consumption depend on mental activity?

What is the impact of mental activity on the energy consumption of the human brain? I am most interested in intellectually demanding tasks (e.g., chess matches, solving a puzzle, taking a difficult ...
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 double-...
34
votes
4answers
22k 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 ...
19
votes
4answers
119k 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 ...
23
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 ...
16
votes
3answers
11k views

Supercomputer Vs Human Brain

With supercomputers doing calculation in petaflops ($10^{15}$ Calculations per Second), have we crossed the speed of Human Brain?
35
votes
1answer
33k 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?
33
votes
3answers
8k 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 ...
24
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 ...
18
votes
2answers
16k 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.
10
votes
1answer
411 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) ?
44
votes
4answers
2k views

Why do men have nipples?

I'd be tempted to call nipples in men vestigial, but that suggests they have no modern function. They do have a function, of course, but only in women. So why do men (and all male mammals) have them?
23
votes
5answers
14k 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
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 ...
15
votes
1answer
2k views

Are human bodies programmed to die?

Following from this question: What is the evolutionary advantage of death?: Is there any evidence that human bodies have systemic self-destruction built into their developmental program? I'm not ...
13
votes
1answer
16k 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?
15
votes
4answers
4k 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 ...
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
1k 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
4k 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 ...
5
votes
1answer
4k views

Why are men stronger than women?

What are the evolutionary explanations for why women are physically weaker than men (on average), and is this difference adaptive? See figure one here. I suppose that something puts pressure on men ...

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