31. Which of the following describes the distribution of thepolar and nonpolar portions of lipids in the lipid bilayer? A).Both polar heads are on the inside of the bilayer and bothhydrophobic tails are on the outside of the bilayer. B). Both polarheads are on the outside of the bilayer and both hydrophobic tailsare on the inside of the bilayer. C). Both the inside and outsideof the bilayer consist of alternating polar heads and nonpolartails. D). Some polar heads are on the inside of the bilayer andsome are on the outside; the hydrophobic tails are similarlydistributed.

33. Which describes the isoelectric point of an amino acid? A).The degree of ionization of the amino acid at pH 7. B). The pH atwhich there is no net charge for the amino acid. C). The pH atwhich the ionized form predominates. D). The pH at which the aminoacid is present as the dipolar ion. CH2 – CONH2 

34. Asparagine (Asn) has an isoelectric point (pI) of 5.4, (H3N+¾CH¾COO- ). Select the correct Zwitterion structure of asparaginein a solution with a pH of 10. CH2 – CONH2 CH2– CONH2   A).H2N¾CH¾COO- B). H3N+ ¾CH¾COOH CH2– CONH2 CH2– CONH2   C).H2N¾CH¾COOH D). H3N+¾CH¾COO-

35. Which functional group is involved in linking together theamino acids of proteins? A). amine B). anhydride C). carbonyl D).carboxyl

36. Select the correct three-letter abbreviation for the orderof amino acids in this tripeptide. O H O H O      H3N+  CH C  N  CH  C  N  CHCO-    CH2OH CH3 H A). AlaGlySerB). GlySerAla C). SerAlaGly D). AlaSerGly

37. The secondary structure of proteins depends primarily onwhich property of amino acids? A). disulfide bonds B). hydrogenbonds C). amide bonds D). polar side chains

38. The beta-pleated sheet represents what level of proteinstructure? A). Primary B). Secondary C). Tertiary D).Quaternary

39. The following will denature proteins EXCEPT A). AgitationB). Acids and bases C). Heavy metal ions D). Freezingtemperature

40. Which of the following is a structural protein? A).cellulose B). collagen C). hemoglobin D). insulin

41. In which of the following is the amino nitrogen also part ofthe side chain? A). cysteine B). glycine C). proline D).tryptophan