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Problem 1b
Classify each of the following proteins according to its function:
a. hemoglobin, oxygen carrier in the blood
Problem 1c
Classify each of the following proteins according to its function:
c. keratin, a protein found in hair
Problem 2b
Classify each of the following proteins according to its function:
a. insulin, a protein needed for glucose utilization
Problem 2c
Classify each of the following proteins according to its function:
c. casein, milk protein
Problem 4
How does the polarity of the R group in leucine compare to the R group in serine?
Problem 6a
Draw the structure for each of the following amino acids at physiological pH:
a. lysine
Problem 7
Classify each of the amino acids in problem 16.5 as polar or nonpolar. If polar, indicate if the R group is neutral, acidic, or basic. Indicate if each is hydrophobic or hydrophilic.
Problem 9d
Write the name for the amino acid represented by each of the following abbreviations:
d. Cys
Problem 10d
Write the name for the amino acid represented by each of the following abbreviations:
d. G
Problem 11b
Draw the condensed structural formula for each of the following peptides, and give its three-letter and one-letter abbreviations:
a. alanylcysteine
Problem 11c
Draw the condensed structural formula for each of the following peptides, and give its three-letter and one-letter abbreviations:
c. glycylalanylvaline
Problem 12b
Draw the condensed structural formula for each of the following peptides, and give its three-letter and one-letter abbreviations:
b. threonylleucine
Problem 12d
Draw the condensed structural formula for each of the following peptides, and give its three-letter and one-letter abbreviations:
d. histidylglycylglutamylisoleucine
Problem 13a
Peptides isolated from rapeseed that may lower blood pressure have the following sequence of amino acids. Draw the structure for each peptide and write the one-letter abbreviations.
a. Arg–Ile–Tyr
Problem 14b
Peptides from sweet potato with antioxidant properties have the following sequence of amino acids. Draw the structure for each peptide and write the one-letter abbreviations.
b. Asn–Tyr–Asp–Glu–Tyr
Problem 16b
Explain why each of the following pairs are complementary proteins:
a. beans and oats
Problem 17
What happens when a primary structure forms a secondary structure?
Problem 19
What is the difference in hydrogen bonding between an α helix and a β−pleated sheet?
Problem 21c
What type of interaction would you expect between the R groups of the following amino acids in a tertiary structure?
c. serine and aspartate
Problem 22a
What type of interaction would you expect between the R groups of the following amino acids in a quaternary structure?
a. phenylalanine and isoleucine
Problem 22d
What type of interaction would you expect between the R groups of the following amino acids in a quaternary structure?
d. alanine and proline
Problem 23a
A portion of a polypeptide chain contains the following sequence of amino acids:
—Leu—Val—Cys—Asp—
a. Which amino acids are likely to be found on the inside of the protein structure? Why?
Problem 23c
A portion of a polypeptide chain contains the following sequence of amino acids:
—Leu—Val—Cys—Asp—
c. How does the primary structure of a protein affect its tertiary structure?
Problem 24a
In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.
a. Where would you expect those amino acids to be located in the tertiary structure?
Problem 24b
In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.
b. Where would you expect the polar R groups to be in the tertiary structure?
Problem 25c
Indicate whether each of the following statements describes primary, secondary, tertiary, or quaternary protein structure:
c. Several polypeptides in a beta-pleated sheet are held together by hydrogen bonds between adjacent chains.
Problem 26a
Indicate whether each of the following statements describes primary, secondary, tertiary, or quaternary protein structure:
b. Protein chains of collagen form a triple helix.
Problem 27b
Indicate the changes in secondary and tertiary structural levels of proteins for each of the following:
b. Prior to giving an injection, the skin is wiped with an alcohol swab.
Problem 28c
Indicate the changes in secondary and tertiary structural levels of proteins for each of the following:
c. To avoid spoilage, seeds are treated with a solution of HgCl2.
Problem 29
Why do chemical reactions in the body require enzymes?