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Questions tagged [molecular-biology]

The study of the molecular processes underlying life.

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208 votes
4 answers
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Why are so few foods blue?

Although blue foods exist, they're rare enough compared to other foods for food preparers to use blue plasters as a convention. The natural colour of a given food is due to pigments that have some ...
J.G.'s user avatar
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50 votes
4 answers
9k views

What is the longest-lasting protein in a human body?

Protein life times are, on average, not particularly long, on a human life timescale. I was wondering, how old is the oldest protein in a human body? Just to clarify, I mean in terms of seconds/...
JalfredP's user avatar
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45 votes
6 answers
2k views

Why are amino acids in biology homochiral?

Why are nearly all amino acids in organisms left-handed (exception is glycine which has no isomer) when abiotic samples typical have an even mix of left- and right-handed molecules?
Poshpaws's user avatar
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35 votes
3 answers
61k 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?
hello all's user avatar
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34 votes
3 answers
4k 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 &...
Matt Cashatt's user avatar
29 votes
3 answers
1k 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  &...
mring's user avatar
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28 votes
2 answers
10k views

What determines which strand of DNA is transcribed by RNA polymerase?

DNA has two strands. How does the machinery of RNA transcription determine which one to transcribe?
CognisMantis's user avatar
26 votes
3 answers
4k views

Does any molecule other than DNA have a double-helical structure?

DNA is known to have a double-helical structure. Do any other molecules have this structure?
The Riddler's user avatar
25 votes
1 answer
2k views

ATP cost for gene expression

How would you estimate the number of ATPs required to transcribe, export and translate a single eukariotic protein?
Gianpaolo R's user avatar
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24 votes
1 answer
4k views

How did scientists discover HIV?

Imagining that we're now in 1983 (when HIV was discovered), there were no modern machines at that time to sequence massive genome extracted from blood. There was a strange disease and no one know what ...
joe's user avatar
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23 votes
4 answers
2k 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?
ghchinoy's user avatar
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22 votes
3 answers
6k views

Effects of mRNA vaccines on human body processes

I would like to understand the effect of an mRNA vaccine on more complex processes in the human body. To what extent does this "artificial", external addition of mRNA interfere with the body'...
choXer's user avatar
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22 votes
1 answer
844 views

Can a human be made with ovum but without sperm?

This article says that scientists were successful in making a mouse using only a sperm and no egg (ovum). The article also states that this procedure could be applicable to humans. However, I want to ...
Mesentery's user avatar
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21 votes
3 answers
16k 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 correctly?
Alex Stacks's user avatar
21 votes
3 answers
7k views

How long can I store extracted RNA?

If I extract RNA from a (leaf tissue) sample using a one-step phenol:chloroform extraction, how long can those samples be stored at -80°C? And how many times can I defrost and refreeze them before ...
Rik Smith-Unna's user avatar
21 votes
1 answer
1k views

Regulation of chromatin structure

Recently, I reviewed the different levels of chromatin structure. The primary level is nucleosomes, where DNA is bound to histones, and has structural similarity to "beads on a string." The secondary ...
Daniel Standage's user avatar
20 votes
6 answers
6k views

Why are some genes dominant over others? What is the mechanism behind it?

If I have a brown eye gene which encodes the protein that is responsible for the brown color and have a blue eye gene as well, what is the reason that my eye color is brown? How does one gene maintain ...
caeruleus's user avatar
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18 votes
1 answer
3k views

Why are sushi proteins called "sushi"? What are the origins of this name?

Does anybody know why complement control proteins (also short consensus repeats) are called "sushi" proteins? Is there any special reason for their name?
Vii Z.'s user avatar
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18 votes
1 answer
367 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 ...
John Smith's user avatar
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18 votes
2 answers
6k views

Why do specifically bananas go brown quicker in the fridge?

Perhaps the title should be: Why don't all fruits containing phenol residues go brown quickly when left in the fridge? Bananas go brown over time because of the oxidation of phenol residues. ...
James's user avatar
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17 votes
2 answers
801 views

Intrinsically disordered proteins as potential drug targets

Intrinsically disordered proteins (IDPs) are a class of proteins that do not adopt a stable secondary or tertiary structure under physiological conditions in vitro, but still have biological functions....
Gergana Vandova's user avatar
17 votes
1 answer
3k views

What did Richard Feynman contribute to molecular biology?

Some time ago, I read James Gleick's "Genius: The Life and Science of Richard Feynman", a wonderful biography of Feynman and, by extension, most of modern physics. In this book, the author mentions ...
terdon's user avatar
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16 votes
3 answers
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Is prion a term used to describe the normal form of the protein as well as the disease causing form?

I've been reading my textbook and it refers to prions as a normal protein with a helpful function but it can turn into a disease causing form. However, I look in my other textbook and it refers to the ...
Aswin Abraham's user avatar
16 votes
7 answers
6k views

Online Molecular and Cellular Biology Video Lectures?

I am looking for video lectures to go through to guide my reading in intro molecular and cellular biology. I've had intro bio and I study evolutionary theory, but my molecule- and cell-level knowledge ...
Jamie Banks's user avatar
16 votes
1 answer
10k views

Is female the default sex in humans?

I was taught in school that female is the default sex in humans based on the following logic: Development into a human male requires the activation of the SRY gene in the foetus. If that doesn't ...
user1205901 - Слава Україні's user avatar
16 votes
2 answers
539 views

How can computer predictions of protein folding be verified computationally?

Currently, there is a lot of research focused on solving the folding patterns of proteins using computers (Folding@Home, https://fold.it/portal/, etc.). The question that I have is: How do you know ...
Stack Tracer's user avatar
15 votes
3 answers
3k views

Is the size of the genome across species roughly the same?

Chromosome number differs across species. Is the amount of DNA comparable between organisms, just being split into smaller chunks in those species with more chromosomes, or do species have different ...
Thaina's user avatar
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15 votes
2 answers
11k views

Why is there more variation in proteins than genes?

The Genome of a cell or organism is the same as that of the entire organism. However, the proteome of an organism is much greater than that of each cell (unless the organism is unicellular). How do ...
Cloud's user avatar
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15 votes
1 answer
2k views

How do ion channels transport only specific ions?

Ion channels, such as $Na^+$ channels and $K^+$ channels, are higly specific for ion permeability. But how do these channels achieve and maintain this specificity? Like how does a $K^+$ channel ...
another 'Homo sapien''s user avatar
15 votes
2 answers
7k views

How does translational coupling work in prokaryotes?

Today I heard about a phenomenon called "translational coupling", where the translation of one protein influences the translation of another protein. The messenger RNA levels don't seem influenced. ...
Royco's user avatar
  • 288
15 votes
4 answers
3k views

Does RNA polymerase move around DNA or does DNA rotate beneath the polymerase?

I'm thinking of the human genome specifically, but more general answers are welcome. As RNA polymerase moves along the DNA helix it follows a single strand. The two DNA strands are unwound locally ...
Dave Gerrard's user avatar
14 votes
3 answers
8k views

How long can E. coli stocks be stored at -20°C?

I'm volunteering for a biohacker lab - biocurious in Sunnyvale. The have a pretty good set of equipment - gel boxes, incubators, but they don't have a -80°C freezer yet. I'd like to set up some ...
shigeta's user avatar
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14 votes
1 answer
108k views

Why do we add salt when precipitating DNA?

All the DNA extraction protocols I have seen involve adding salts to the extraction buffer. What is the purpose of the salts? What happens if they aren't included?
Rik Smith-Unna's user avatar
14 votes
3 answers
13k views

How does the body switch between aerobic and anaerobic respiration?

Lets take the case of a person doing heavy exercise. Aerobic respiration is taking place, but oxygen is about to be finished up. Glycolysis occurs, Krebs cycle finishes. Now NADH and FADH2 enter ...
another 'Homo sapien''s user avatar
13 votes
3 answers
2k views

Does a man contain all the genes needed to make a woman?

This question is brought on by a Sci Fi novel I am thinking about writing. The plot device involves a colonist in charge of building a population on a new planet who loses his supply of embryos and so ...
wedstrom's user avatar
  • 233
13 votes
2 answers
608 views

Are codons that map to the same amino acids interchangeable?

From wikipedia, in the section on the RNA codon table, I see a mapping between codons and amino acids. There, Valine is related to GUU, GUA, GUG, GUC. Does it mean in the same context that these ...
Yehosef's user avatar
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13 votes
2 answers
11k views

Why is uracil, rather than thymine, used in RNA?

This question was posed on SE Biology some time ago, but all the answers, including the accepted one, answered a different question instead: “Why is thymine, rather than uracil, used in DNA?”. I ...
David's user avatar
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13 votes
1 answer
727 views

When did CRISPR/Cas9 evolve and what is the likelihood that a superior system for live cell genome editing has already evolved on earth since then?

I've read that CRISPR/Cas9 is currently being implemented and tested for its ability to edit genomes in live cells, and that it is supplanting other genome editing tools in labs, such as TALENs and ...
Jesse W. Collins's user avatar
13 votes
1 answer
2k views

What is, (and what isn't) "kinetic replication" as it applies to molecules and to living organisms?

CNN's World's first living robots can now reproduce, scientists say describes "xenobots"; clusters of stem cells that move around and by this motion occasionally push enough free stem cells ...
uhoh's user avatar
  • 5,486
13 votes
1 answer
203 views

What actually kills a plant that requires winter dormancy if it is kept indoors all year?

In bonsai practice, beginners will commonly purchase a juniper (often Juniperus procumbens 'Nana'), which is an outdoor tree, and keep it inside all year. The tree invariably dies. It is commonly ...
cape1232's user avatar
  • 239
12 votes
3 answers
49k views

Why do 60S & 40S ribosomal subunits make an 80S ribosome (not 100S)?

Why do 60S & 40S subunits make an 80S (not 100S) ribosome and, similarly, 50S & 30S make 70S? 60+40 is not equal to 80, nor is 50+30 equal to 70, so why are the subunits of the 80S and 70S ...
roxaite's user avatar
  • 427
12 votes
2 answers
87k views

What is the function of the RNA primer in DNA replication?

During DNA replication, RNA primase puts an RNA primer in the lagging strand. What is the function of this RNA primer? Why can't the enzymes put DNA fragments directly?
Rafique's user avatar
  • 445
12 votes
2 answers
353 views

Is there a program that simulates biology on a molecular level?

Is there a computer program that simulates biology on a molecular level? Software that has rules that simulates the rules of molecular-biology?
David Walz's user avatar
12 votes
2 answers
59k views

Why is SOC medium recommended for transformations?

In pretty much every transformation protocol I've seen SOC medium is used to grow the bacteria for a short while after the tranformation and before plating. I've usually substituted LB medium for ...
Mad Scientist's user avatar
12 votes
2 answers
2k views

Why aren't 'exons' named 'introns'?

Why are introns called 'introns' when they are the actual ones who are getting spliced out from the pre-mRNA. Shouldn't exons be named introns as they are the ones that are 'in' and are not 'exiting'? ...
Jewel Johnson's user avatar
12 votes
4 answers
16k views

Why is AUG the initiation codon?

Is there any reason why AUG is the initiation codon? Can’t translation start with different codons?
biogirl's user avatar
  • 8,601
12 votes
2 answers
4k views

Why are restriction enzymes not frozen?

We all know restriction enzymes are proteins, but we never freeze them. They are instead provided in high glycerol containing solutions by companies and stored at -20C. Is there a reason why this is ...
gkadam's user avatar
  • 1,666
12 votes
1 answer
16k views

How tolerant are ants to cold?

There was a trail of what are commonly known as sugar ants (small, brown, hyperactive) in my kitchen. Three of them walked onto an ice tray placed in their path. They only walked a short distance on ...
daniel's user avatar
  • 2,799
12 votes
1 answer
709 views

What is the half-life of dNTPs at 95 °C?

I'm looking for the half-life of dNTPs, either as a whole or broken into individual bases, at 95 °C (or similar). A titration would be great if that exists. I can provide more specifics if need be, ...
metaditch's user avatar
  • 121
12 votes
3 answers
27k views

Why does replication require primers while transcription does not?

In transcription, there is no need for any primer. I guess the basic mechanism of DNA polymerase & RNA polymerase is the same. So why does replication have the need for a primer?
anamitra ruj's user avatar

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