WGU C785 Biochemistry Exam
Questions & Solutions Latest
2026/2027
Unit 1: Amino Acids, Proteins, and Enzymes
1. What is the general structure of an amino acid?
ANSWER ✓ A central (alpha) carbon bonded to an amino group (-NH2), a carboxyl
group (-COOH), a hydrogen atom, and a unique variable side chain (R-group).
2. What determines the unique chemical properties of an amino acid?
ANSWER ✓ The side chain (R-group).
3. Which amino acids are positively charged (basic) at physiological pH?
ANSWER ✓ Histidine (His, H), Lysine (Lys, K), Arginine (Arg, R).
4. Which amino acids are negatively charged (acidic) at physiological pH?
ANSWER ✓ Glutamic acid (Glu, E), Aspartic acid (Asp, D).
5. Which amino acids contain sulfur?
ANSWER ✓ Cysteine (Cys, C) and Methionine (Met, M).
6. Which amino acid forms disulfide bonds?
ANSWER ✓ Cysteine. The bond forms between the sulfur atoms of two cysteine
residues.
7. What is the primary structure of a protein?
ANSWER ✓ The unique linear sequence of amino acids.
, 8. What is the secondary structure of a protein?
ANSWER ✓ Local folding patterns stabilized by hydrogen bonding between the carbonyl
oxygen of one amino acid and the amide hydrogen of another. Examples include alpha-
helices and beta-pleated sheets.
9. What is the tertiary structure of a protein?
ANSWER ✓ The three-dimensional conformation of a single polypeptide chain,
stabilized by interactions between side chains (hydrophobic interactions, hydrogen
bonds, ionic bonds, disulfide bridges).
10. What is the quaternary structure of a protein?
ANSWER ✓ The association of multiple polypeptide subunits into a functional protein
complex (e.g., hemoglobin).
11. What is the function of a kinase?
ANSWER ✓ An enzyme that catalyzes the transfer of a phosphate group from ATP to a
substrate (phosphorylation).
12. What is the function of a phosphatase?
ANSWER ✓ An enzyme that catalyzes the removal of a phosphate group from a
substrate (dephosphorylation).
13. What is the function of a phosphorylase?
ANSWER ✓ An enzyme that adds a phosphate group by breaking a bond using
inorganic phosphate (e.g., glycogen phosphorylase).
14. How does phosphorylation typically alter enzyme activity?
ANSWER ✓ It can either activate or inactivate an enzyme by inducing a conformational
change.
15. What is an allosteric regulator?
ANSWER ✓ A molecule that binds to a site other than the active site (allosteric site) and
causes a conformational change that affects enzyme activity.
16. How does a competitive inhibitor affect enzyme kinetics (Vmax and Km)?
Questions & Solutions Latest
2026/2027
Unit 1: Amino Acids, Proteins, and Enzymes
1. What is the general structure of an amino acid?
ANSWER ✓ A central (alpha) carbon bonded to an amino group (-NH2), a carboxyl
group (-COOH), a hydrogen atom, and a unique variable side chain (R-group).
2. What determines the unique chemical properties of an amino acid?
ANSWER ✓ The side chain (R-group).
3. Which amino acids are positively charged (basic) at physiological pH?
ANSWER ✓ Histidine (His, H), Lysine (Lys, K), Arginine (Arg, R).
4. Which amino acids are negatively charged (acidic) at physiological pH?
ANSWER ✓ Glutamic acid (Glu, E), Aspartic acid (Asp, D).
5. Which amino acids contain sulfur?
ANSWER ✓ Cysteine (Cys, C) and Methionine (Met, M).
6. Which amino acid forms disulfide bonds?
ANSWER ✓ Cysteine. The bond forms between the sulfur atoms of two cysteine
residues.
7. What is the primary structure of a protein?
ANSWER ✓ The unique linear sequence of amino acids.
, 8. What is the secondary structure of a protein?
ANSWER ✓ Local folding patterns stabilized by hydrogen bonding between the carbonyl
oxygen of one amino acid and the amide hydrogen of another. Examples include alpha-
helices and beta-pleated sheets.
9. What is the tertiary structure of a protein?
ANSWER ✓ The three-dimensional conformation of a single polypeptide chain,
stabilized by interactions between side chains (hydrophobic interactions, hydrogen
bonds, ionic bonds, disulfide bridges).
10. What is the quaternary structure of a protein?
ANSWER ✓ The association of multiple polypeptide subunits into a functional protein
complex (e.g., hemoglobin).
11. What is the function of a kinase?
ANSWER ✓ An enzyme that catalyzes the transfer of a phosphate group from ATP to a
substrate (phosphorylation).
12. What is the function of a phosphatase?
ANSWER ✓ An enzyme that catalyzes the removal of a phosphate group from a
substrate (dephosphorylation).
13. What is the function of a phosphorylase?
ANSWER ✓ An enzyme that adds a phosphate group by breaking a bond using
inorganic phosphate (e.g., glycogen phosphorylase).
14. How does phosphorylation typically alter enzyme activity?
ANSWER ✓ It can either activate or inactivate an enzyme by inducing a conformational
change.
15. What is an allosteric regulator?
ANSWER ✓ A molecule that binds to a site other than the active site (allosteric site) and
causes a conformational change that affects enzyme activity.
16. How does a competitive inhibitor affect enzyme kinetics (Vmax and Km)?
