Ph has a major influence on protein structure by altering electrostatic interactions. in order to illustrate this point, let us think about polylysine (a polypeptide chain consisting of only l-lysine residues). at ph 10 and above, polylysine forms an ahelix. at a ph of 7 and below, however, this same polypeptide chain assumes an unfolded conformation (often referred to as ‘random coil’ or ‘random conformation’).

1) can you explain why this transition occurs at phs below the pka of lys?

2) what other residue(s) might you expect to show a similar pattern of ph-dependent folding and unfolding?

3) the residue(s) you might expect based on charge to be capable of forming α-helices do not do so in water when they alone make up a polypeptide chain. can you come up with a reasonable explanation for why this might be?

4) speculate on what you think might happen to the ph-dependence of α-helix formation if you had a polypeptide chain consisting of both glutamate and lysine residues.

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above

Recently, crops of vegetables such as lettuce and green onions have been contaminated, while they are still on the farm, with bacteria that cause food poisoning. how will science influence the way the government responds to prevent an increase in food-borne diseases? because science has shown that lettuce and green onions are not nutritionally valuable, the government may pass laws that ban the sale of lettuce and green onions. because science has shown that there is no way to prevent bacterial contamination, the government may pass laws that punish businesses that buy lettuce and green onions. because science has shown that the washing of hands prevent the spread of infectious diseases among people, the government may pass laws that require hand washing by everyone who handles food. because science has shown there are ways to find the source of the contamination, the government may pass laws that require farm practices that reduce the contamination of lettuce and green onions.

Explain how light energy is turned into chemical energy? ! due tomorrow!