Problem Set 2 Answers - MCB102 - Problem Set 2 This...

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MCB102 - Problem Set 2 This ungraded problem set covers the material discussed in Lectures 5-7. See if you can work out the answers yourself, before looking at the answers that will be posted in a few days. Also, try the problems at the end of Chapters 4-5 in the Lehninger textbook. If you need help, talk to your GSIs or to me. 1. Summarize the similarities and differences between alpha helix and beta pleated sheet structures. See lecture notes. 2. When one examines a Ramachandran plot of the phi and psi angles that occur for glycine residues in actual proteins, it is noticed that some angles occur in “forbidden regions” of the plot. Explain this. Still considering Ramachandran plots, explain why polypeptides assume only a limited number of regular structures. ANS: Because glycine’s R group is H, much of the steric hinderance that creates the “forbidden regions” is not present. Only those phi and psi angles in “allowed” regions are available to form repeating 2° structure. 3. The principle driving force in the folding of some proteins is the movement of hydrophobic amino acid sidechains out of the aqueous environment. Explain. ANS: By folding and formation of a hydrophobic core, the non-favorable entropy-related interactions of water and the hydrophobic side-chains is eliminated. 4. Polyglutamate and polylysine peptides both form alpha-helices in solution.
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Problem Set 2 Answers - MCB102 - Problem Set 2 This...

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