Question

1. Given the following peptide, which of the following statements is true?

Question options:

a) The N-terminal residue is leucine.

b)This peptide contains 4 amino acid residues.

c) The peptide contains a total of 6 ionizable groups.

d) The net charge of this peptide at pH 7 is +1 Locate any peptide bond along the backbone of the given peptide.

e) The bond between the C (of the C=O) and the N (of the N-H) of a peptide bond has free (unrestricted) rotation.

f) Three of the above are correct.

0 0 CH CH CH CH CH CH CH CH-CH OH CH CH CH3

2. Which of the following amino acids is properly paired with a property?

Question options:

a)	glycine: contains a polar R group
b)	proline: presence in polypeptide may cause abrupt change in direction and/or restricted geometry
c)	leucine: basic amino acid
d)	aspartate: generally positively charged at neutral pH
e)	valine: an amino acid that is ideal for the transfer of protons within the catalytic site of enzymes due to the presence of significant amounts of both the protonated and deprotonated forms of its side chain at biological pH

3. Which of the following is correct regarding lipids?

Question options:

a)	All hydrolyzable lipids contain one or more amide linkages.
b)	The major function of nonhydrolyzable lipids is to serve as efficient energy stores.
c)	All nonhydrolyzable lipids are arachidonic acid derivatives.
d)	All hydrolyzable lipids contain one or more fatty acids components.
e)	More than one of the above are correct.

4. The rate at which the cell synthesizes RNA in E. coli is greatest for ________ RNA while the most abundant type of RNA is _________.

Question options:

a)	messenger; ribosomal
b)	ribosomal; messenger
c)	transfer; ribosomal
d)	transfer; transfer
e)	None of the above

Thank you so much for your help!

Answer 1

a) H2N-CH-C-NH-CH-C NH-CH-C-NH-CH-C NH-CH-C OH CH CH CH-CH3 OH CH NH NH2 This is the N-terminus part of the peptide This N-terminal residue is Alanine. (not leucine) So option a False H2N-CH-C-NH-CH-C-NH-CH-C-NH-CH CH CH NH-CH-C-OH =0 OH CH Alanine Aspartic acid NH2 NH2 Leucine Lysine Lysine This is a penta-peptide. That is it is formed by 5 aminoacid residues So option b False H2N-CH-C-NH-CH-C-NH-CH-CNH-CH-C NH-CH он CH -CH OH CH CH NH NH In a peptide, free -NH2 and -COOH groups are the ionizable groups. In this peptide there are two -COOH and 3 -NH2 groups are present. So the total number of ionizable groups 5 So option c False

CH CEO CH CH CH CH 田NH3 CH CH CH CH 田NH, CH CH-CH.2 CH CH At pH=7, (generally at its isoelectric point) the aminoacid exists as Zwitter ion So the total charge on the peptide (+1) 1)(+1) (+1)-1) +1 So option d is TRUE e) the C-N Bond of the amide bond has ristriced rotation due to the patrial double bond character of C-N bond C_NH Partial double bond option e is False So option d is the right answer.