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From the era before Sanger sequencing was invented.


Nov
17
revised Why are transmembrane proteins difficult to crystallise?
tidying plus some pedantry
Nov
17
revised Why use DNA polymerase in making cDNA?
edited title
Nov
17
answered How to identify active protein in a complex mixture?
Nov
16
revised Stability of helical strands of DNA?
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Nov
16
answered Stability of helical strands of DNA?
Nov
15
comment Why is fructose not glucose the main energy source of sperm?
I admit that I have not come up with an answer, but it seems to me that maybe there is something else about fructose that makes it a better choice. Maybe it has some function, other than as a C source, in the fluid. It may be relevant that it is much more soluble than glucose, although the concentration that you quote is way below the solubility limit for either sugar.
Nov
15
answered Gel electrophoresis question
Nov
15
comment Energetics and Products of Pepsin/HCl Protein Digestion
The HCl isn't really involved in the reaction at all, except in the sense that it drives the pH down. There may be some binding and/or release of protons during the autocatalytic process. I haven't been able to find anything about the free energy change that accompanies the reaction. Of course the entropy will increase (1 molecule > 2 molecules), so it is even possible that the enthalpy term (your ?joules I assume) would be positive.
Nov
15
comment Are Asians more genetically homogenous than other races?
This Wikipedia page is a good source en.wikipedia.org/wiki/Human_genetic_variation The argument is that during the out-of-Africa migrations only a small sample of the total genetic variation left Africa. Those who remained inherited all of the existing variation. Detailed information at the WP page.
Nov
15
comment Hardy Weinberg Equilibrium problem
thanks @fileunderwater, I've been tearing my hair out over this! You should post your calculation - I expect it is more elegant than mine.
Nov
15
comment Why is fructose not glucose the main energy source of sperm?
Neither of these arguments make sense to me. Firstly, if there was an advantage to using fructose amongst bacteria that might encounter semen then they would evolve to exploit the niche. I note that E. coli for example will quite happily use fructose as C source. On the second point, I don't see how the fact that you can make fructose from glucose without using ATP is an argument against just using glucose in the first place. In any case I think that arguments from energetic efficiency are rarely convincing.
Nov
15
comment Protein purification methods
Well, I see that this is the accepted answer, and I don't disagree with any of it, but it isn't really the answer to the question that was posed. In terms of a purification factor (e.g. increase in specific activity of an enzyme), affinity purification will win out every time.
Nov
15
comment Are Asians more genetically homogenous than other races?
I think you'll find that Africans are the most genetically heterogeneous.
Nov
15
answered Hardy Weinberg Equilibrium problem
Nov
14
revised Western blotting questions?
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Nov
14
revised Protein purification methods
added 3 characters in body
Nov
14
comment Protein purification methods
The fact that all of the tagging methods used for purification of proteins expressed from cloned genes (his tags, FLAG tags etc.) are designed to facilitate affinity purification approaches underscores this answer.
Nov
14
revised Energetics and Products of Pepsin/HCl Protein Digestion
clarification
Nov
14
revised Energetics and Products of Pepsin/HCl Protein Digestion
deleted 3 characters in body
Nov
14
answered Standard letter for 5-methylcytosine