37
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 ...
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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 ...
- 68k
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 ...
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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 ...
- 4,678
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 ...
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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.
...
- 3,204
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 ...
- 14.1k
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 ...
- 17.6k
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 ...
- 14.2k
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 ...
- 9,112
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. ...
- 6,869
9
votes
Accepted
Pedigree Analysis: Problem
The key here is that it is a question about mitochondrial DNA. mtDNA in humans is inherited maternally (from the mother). Both sons and daughters inherit mtDNA, but only the daughters will pass it on ...
- 2,472
9
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 ...
- 51.5k
8
votes
Accepted
How to do multiple sequence alignment?
MSA Tools
compare the amino acid sequence of protein 1 with nine homologous proteins and make a multi-alignment of the sequences.
EBI have a portal for many MSA tools and there are also other MSA ...
- 11.3k
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=...
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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 ...
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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 ...
- 44k
7
votes
Accepted
Gene and alleles
Alleles are basically subtypes of a gene. At the time of Mendel, the molecular nature of inheritance was not known so the original definition of gene refers to "some" inheritable molecular entity ...
- 35.2k
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 ...
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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 ...
- 1,679
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
(...
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6
votes
Accepted
What is enantiostasis?
Both are ways for an organism to adapt to the environment, but enantiostasis focuses on maintaining functionality while homeostasis focuses on maintaining a stable internal environment.
For example, ...
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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. ...
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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 ...
- 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 ...
- 24.3k
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 ...
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 ...
- 617
5
votes
How is the probability of a sequence occuring with BLAST calculated?
According to BLAST documentation statistics of local sequence alignment, when doing database searches, is done
by treating the database as a single long sequence of length N.
N is therefore a sum ...
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