38 votes
Accepted

Who are humans' closest relatives, after primates?

Short answer It is a flying lemur (there exist only 2 species). Flying lemurs and primates are together a sister clade to treeshrews. Easy source of information Have a look at the post The best ...
Remi.b's user avatar
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29 votes

Solving Hardy Weinberg problems

Here is a tutorial to perfectly understand Hardy-Weinberg Rule! If you feel like you just need a brief reminder, you can skip the text until the section In short... and try out the exercises just to ...
Remi.b's user avatar
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24 votes

Who are humans' closest relatives, after primates?

The most closely related animals to primates are colugos (order Dermoptera). The next most closely related after colugos are tree shrews (order Scandentia). The next most closely related after tree ...
Gwen's user avatar
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20 votes
Accepted

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

The terms intron and exon were coined by Walter Gilbert in a renowned 'News and Views' article, Why Genes in Pieces, published in the journal Nature in 1978. Introns are the intragenic regions and ...
user338907's user avatar
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17 votes
Accepted

Which type of test tube should not be used for blood collection?

Your reasoning is sound and correct. The answer key is wrong. An unclotted blood sample needs something to prevent clotting. Extracellular calcium is required for both the coagulation cascade and ...
De Novo's user avatar
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13 votes

What is the difference between the evolution of fins in whales and fish?

I agree with you that the question is ambiguous, and also that the most sensible answer would be C. However, one could make a more or less reasonable argument in favor of several other answers, too. ...
Ilmari Karonen's user avatar
13 votes
Accepted

Can enzymes catalyze thermodynamically unfavorable reactions?

Enzymes can catalyze a thermodynamically unfavorable reaction by coupling it with a thermodynamically favorable reaction. Most often, enzymes use ATP hydrolysis reaction (energetically favorable) as a ...
another 'Homo sapien''s user avatar
13 votes

Can enzymes catalyze thermodynamically unfavorable reactions?

Can enzymes catalyze thermodynamically unfavourable reactions? Enzymes don't change the equilibrium of a reaction, but the fact that an equilibrium exists means that the reaction proceeds in both the ...
canadianer's user avatar
  • 17.7k
11 votes

Which of the following lacks DNA?

There are two answers if the question refers to genomic DNA (neither enucleated ova nor mature RBCs have genomic DNA). However, since the question doesn't specify genomic DNA, we can exclude ...
iayork's user avatar
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11 votes

why does translation occur more frequently than transcription?

The simple answer Under the assumption that each mRNA molecule is translated at least once, by necessity translation will happen more often than transcription. This is because the only way to get a ...
Maximilian Press's user avatar
10 votes
Accepted

Which bacteria takes the longest to double?

There is no answer to your question The doubling time of a bacterium is dependent on the conditions: primarily on the temperature and the availability of nutrients, but other factors can apply. ...
Jack Aidley's user avatar
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10 votes
Accepted

Why were there relatively fewer papers about cell fusion before the 1950s?

Since you need to be able to grow cells for studying their interactions, I think the main reason for this is the development of cell culture techniques in the late 1940s and early 1950s. As an example ...
Chris's user avatar
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8 votes
Accepted

Denaturation of protein

If you think about the boiling of water, I'm sure you can understand that heat breaks hydrogen bonds. Next consider that the hydrophobic effect is driven entropically and so, by the equation $\Delta G=...
canadianer's user avatar
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8 votes
Accepted

What’s the Difference Between Grass and Sedge?

Short answer Sedges have edges, and they're in different families. See Minnesota Wildflowers for a great summary with images. Long answer Both are in the order Poales, but they are in different ...
theforestecologist's user avatar
8 votes
Accepted

How does increased resistance to flow decrease blood pressure?

There is not enough information in the question to solve it. The answer key from the original question makes a logical error: Viscosity is directly proportional to resistance. This is true. An ...
Bryan Krause's user avatar
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7 votes
Accepted

Is the start codon regarded as part of the UTR (untranslated region)?

Because the start codon is translated into methionine, it clearly can not be part of the 5'-untranslated region, as @Johnny writes in his answer. The more contentious question would be for the stop ...
David's user avatar
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7 votes

Solving Hardy Weinberg problems

Lets say there are 2 alleles. One of them is represented by B and other by b. Both will have some frequency at a specific time in a population. Now, frequency is number of that allele divided by total ...
YAHB's user avatar
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7 votes

Frequency of dominant phenotype (Hardy-Weinberg)

p = p(a) = 0.6 q = p(A) = 0.4 Frequency of homozygous recessive, aa = p2 = 0.36 All other genotypes have dominant phenotype therefore the frequency of the dominant phenotype is 1-0.36 = 0.64 (...
Alan Boyd's user avatar
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6 votes
Accepted

What is the difference between the evolution of fins in whales and fish?

Short answer d) is definitely correct. Background The crucial element is that whales returned from land to the sea and re-evolved fins. a) is incorrect, as the common ancestor may not have had fins. ...
AliceD's user avatar
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6 votes

Homework question on chemically defined medium

A chemically defined medium is, according to this Wikipedia article: ... a growth medium suitable for the in vitro cell culture of human or animal cells in which all of the chemical components ...
airhuff's user avatar
  • 290
6 votes
Accepted

How does aminoacyl-tRNA synthetase recognize different tRNAs?

You give the answer in your question: binding areas that recognize a particular tRNA through unique identity sites at the acceptor stem and/or anticodon loop of the tRNA. The point is that ...
David's user avatar
  • 25.7k
6 votes

How do I determine this logistic growth model formula?

The growth of the yeast can be studied with a Logistic model (i.e. differential equation) as follows: $$ \frac{dX}{dt}=\mu X \left(1 - \frac{X}{X_{max}} \right) $$ This is an ordinary differential ...
Alejandro Vignoni's user avatar
6 votes

Why is Ibuprofen contraindicated in asthma patients?

Ibuprofen is an NSAID. So it acts by inhibiting COX (Cyclooxygenase) enzyme. What it signifies is that, if COX enzyme has been blocked, the PUFA (say arachidonic acid, here) will be converted to ...
ANA negative's user avatar
5 votes
Accepted

How can I make a protein interaction/protein-complex network?

This is not a trivial task depending on how well studied your network is or what information you want to gather. It sounds like an interaction dataset is what you want rather than scouring the PDB for ...
James's user avatar
  • 11.3k
5 votes
Accepted

What is the actual storage form of energy in muscles? ATP or Glycogen?

This is a typical MCQ which in order to answer you have to have been at somebody’s lectures or be able to read his mind. The antithesis of education! Cells don’t store energy like car batteries. ...
David's user avatar
  • 25.7k
5 votes

What is the actual storage form of energy in muscles? ATP or Glycogen?

If you are only given glycogen and ATP as choices, then glycogen is the correct answer. The reason for this is, that muscle cells need ATP also for other very important processes (such as keeping the ...
Thawn's user avatar
  • 1,239
5 votes
Accepted

Why is the Pentose Phosphate Pathway so active in erythrocytes?

No. Your supposition is incorrect — the phosphate in glyceraldehyde 3-phosphate has to come from somewhere, and it comes from glucose 6-phosphate. The reason a second ATP is required before you get to ...
David's user avatar
  • 25.7k
5 votes

Which organelle is the easiest to see in a cell?

A quick google revealed this slideshow that says the nucleus is the easiest organelle to see. Generally, this is what is taught in schools worldwide. Note that mature red blood cells don't have a ...
James's user avatar
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