WGU C785
Biochemistry Final
Exam Practice 2026
This exam covers key concepts from the WGU C785 Biochemistry course,
including amino acids and proteins, enzymes, carbohydrates, lipids, nucleotides,
DNA/RNA, and metabolic pathways.
Section 1: Amino Acids and Protein Structure (Questions 1-25)
1. Which of the following amino acids is classified as nonpolar and aliphatic?
A. Serine
B. Lysine
C. Valine
D. Aspartate
ANSWERC
,Rationale: Valine has a branched aliphatic side chain, making it nonpolar and hydrophobic. Serine is
polar, Lysine is basic, and Aspartate is acidic.
2. At a pH of 7.4, what is the net charge of the amino acid lysine (pKa of side chain is 10.5)?
A. +2
B. +1
C. 0
D. -1
ANSWERB
Rationale: The alpha-carboxyl group (pKa ~2) is deprotonated (-1), the alpha-amino group (pKa ~9) is
protonated (+1), and the side chain amino group (pKa ~10.5) is protonated (+1). The net charge is (+1) +
(+1) + (-1) = +1.
3. Which amino acid contains a hydroxyl group in its side chain?
A. Alanine
B. Threonine
C. Methionine
D. Phenylalanine
ANSWERB
Rationale: Threonine, like serine and tyrosine, has a hydroxyl (-OH) group in its side chain, which makes
it polar.
4. The peptide bond is formed between which two functional groups?
A. Two carboxyl groups
B. Two amino groups
,C. An amino group and a carboxyl group
D. A hydroxyl group and a carboxyl group
ANSWERC
Rationale: A peptide bond is an amide bond formed via a dehydration (condensation) reaction between
the alpha-carboxyl group of one amino acid and the alpha-amino group of another.
5. What is the primary structure of a protein?
A. The linear sequence of amino acids
B. The local folding of the polypeptide chain into alpha-helices and beta-sheets
C. The overall 3D shape of a single polypeptide chain
D. The arrangement of multiple polypeptide subunits
ANSWERA
Rationale: Primary structure is simply the order of amino acids in the polypeptide chain, determined by
the gene sequence.
6. Which type of bond is primarily responsible for stabilizing the alpha-helix and beta-sheet structures?
A. Peptide bonds
B. Hydrogen bonds
C. Disulfide bonds
D. Hydrophobic interactions
ANSWERB
Rationale: Secondary structure (alpha-helices and beta-sheets) is stabilized by hydrogen bonds between
the carbonyl oxygen and the amide hydrogen of the polypeptide backbone.
, 7. Sickle cell anemia is caused by a mutation that replaces which amino acid with valine in the beta-
globin chain?
A. Glutamate
B. Lysine
C. Glycine
D. Aspartate
ANSWERA
Rationale: A single point mutation replaces a polar, negatively charged glutamate with a nonpolar,
hydrophobic valine. This change in primary structure alters the protein's tertiary structure, causing it to
polymerize.
8. Which level of protein structure is defined by the interaction between multiple polypeptide subunits?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
ANSWERD
Rationale: Quaternary structure refers to the assembly of multiple polypeptide chains (subunits) into a
single functional protein complex, like hemoglobin.
9. The unfolding of a protein, which results in the loss of its function, is called:
A. Hydrolysis
B. Denaturation
C. Oxidation
D. Hydrophobic
Biochemistry Final
Exam Practice 2026
This exam covers key concepts from the WGU C785 Biochemistry course,
including amino acids and proteins, enzymes, carbohydrates, lipids, nucleotides,
DNA/RNA, and metabolic pathways.
Section 1: Amino Acids and Protein Structure (Questions 1-25)
1. Which of the following amino acids is classified as nonpolar and aliphatic?
A. Serine
B. Lysine
C. Valine
D. Aspartate
ANSWERC
,Rationale: Valine has a branched aliphatic side chain, making it nonpolar and hydrophobic. Serine is
polar, Lysine is basic, and Aspartate is acidic.
2. At a pH of 7.4, what is the net charge of the amino acid lysine (pKa of side chain is 10.5)?
A. +2
B. +1
C. 0
D. -1
ANSWERB
Rationale: The alpha-carboxyl group (pKa ~2) is deprotonated (-1), the alpha-amino group (pKa ~9) is
protonated (+1), and the side chain amino group (pKa ~10.5) is protonated (+1). The net charge is (+1) +
(+1) + (-1) = +1.
3. Which amino acid contains a hydroxyl group in its side chain?
A. Alanine
B. Threonine
C. Methionine
D. Phenylalanine
ANSWERB
Rationale: Threonine, like serine and tyrosine, has a hydroxyl (-OH) group in its side chain, which makes
it polar.
4. The peptide bond is formed between which two functional groups?
A. Two carboxyl groups
B. Two amino groups
,C. An amino group and a carboxyl group
D. A hydroxyl group and a carboxyl group
ANSWERC
Rationale: A peptide bond is an amide bond formed via a dehydration (condensation) reaction between
the alpha-carboxyl group of one amino acid and the alpha-amino group of another.
5. What is the primary structure of a protein?
A. The linear sequence of amino acids
B. The local folding of the polypeptide chain into alpha-helices and beta-sheets
C. The overall 3D shape of a single polypeptide chain
D. The arrangement of multiple polypeptide subunits
ANSWERA
Rationale: Primary structure is simply the order of amino acids in the polypeptide chain, determined by
the gene sequence.
6. Which type of bond is primarily responsible for stabilizing the alpha-helix and beta-sheet structures?
A. Peptide bonds
B. Hydrogen bonds
C. Disulfide bonds
D. Hydrophobic interactions
ANSWERB
Rationale: Secondary structure (alpha-helices and beta-sheets) is stabilized by hydrogen bonds between
the carbonyl oxygen and the amide hydrogen of the polypeptide backbone.
, 7. Sickle cell anemia is caused by a mutation that replaces which amino acid with valine in the beta-
globin chain?
A. Glutamate
B. Lysine
C. Glycine
D. Aspartate
ANSWERA
Rationale: A single point mutation replaces a polar, negatively charged glutamate with a nonpolar,
hydrophobic valine. This change in primary structure alters the protein's tertiary structure, causing it to
polymerize.
8. Which level of protein structure is defined by the interaction between multiple polypeptide subunits?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
ANSWERD
Rationale: Quaternary structure refers to the assembly of multiple polypeptide chains (subunits) into a
single functional protein complex, like hemoglobin.
9. The unfolding of a protein, which results in the loss of its function, is called:
A. Hydrolysis
B. Denaturation
C. Oxidation
D. Hydrophobic
