C785 Biochemistry Module 4: DNA, RNA, and Protein Synthesis 2026
|WGU
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to unzip the
DNA strand.
2. In DNA replication, which enzyme joins the Okazaki fragments together?
A. Topoisomerase
B. DNA Ligase
C. DNA Polymerase III
D. RNA Polymerase
Answer: B
Rationale: DNA Ligase seals the nicks in the sugar-phosphate backbone, joining fragments
into a continuous strand.
,3. Which of the following describes the directionality of DNA synthesis?
A. 3’ to 5’
B. N-terminus to C-terminus
C. 5’ to 3’
D. Randomly
Answer: C
Rationale: DNA polymerase can only add new nucleotides to the 3’ OH group of a growing
strand, meaning synthesis always occurs in the 5’ to 3’ direction.
4. What is the primary role of Primase in DNA replication?
A. To stabilize single-stranded DNA
B. To remove mismatched bases
C. To synthesize a short RNA primer
D. To synthesize the leading strand
Answer: C
Rationale: DNA polymerase requires an existing 3’ end to start synthesis; Primase
provides this via an RNA primer.
5. According to Chargaff’s rules, if a DNA sample contains 20% Adenine, what is
the percentage of Guanine?
A. 20%
B. 80%
C. 30%
D. 40%
Answer: C
Rationale: If A=20%, then T=20% (Total 40%). The remaining 60% must be split equally
between G and C, so G=30%.
, 6. Which process involves making an RNA copy of a DNA sequence?
A. Transcription
B. Replication
C. Translation
D. Mutation
Answer: A
Rationale: Transcription is the synthesis of RNA from a DNA template.
7. Which type of RNA carries the genetic code from the nucleus to the
ribosome?
A. tRNA
B. rRNA
C. mRNA
D. snRNA
Answer: C
Rationale: mRNA (messenger RNA) serves as the intermediate between DNA and protein
synthesis.
8. What is the function of the TATA box in eukaryotes?
A. It is a stop signal for translation
B. It acts as a promoter sequence for transcription
C. It marks the start of an intron
D. It binds to the tRNA anticodon
Answer: B
Rationale: The TATA box is a DNA sequence that indicates where a genetic sequence can
be read and decoded, helping position RNA polymerase.
|WGU
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to unzip the
DNA strand.
2. In DNA replication, which enzyme joins the Okazaki fragments together?
A. Topoisomerase
B. DNA Ligase
C. DNA Polymerase III
D. RNA Polymerase
Answer: B
Rationale: DNA Ligase seals the nicks in the sugar-phosphate backbone, joining fragments
into a continuous strand.
,3. Which of the following describes the directionality of DNA synthesis?
A. 3’ to 5’
B. N-terminus to C-terminus
C. 5’ to 3’
D. Randomly
Answer: C
Rationale: DNA polymerase can only add new nucleotides to the 3’ OH group of a growing
strand, meaning synthesis always occurs in the 5’ to 3’ direction.
4. What is the primary role of Primase in DNA replication?
A. To stabilize single-stranded DNA
B. To remove mismatched bases
C. To synthesize a short RNA primer
D. To synthesize the leading strand
Answer: C
Rationale: DNA polymerase requires an existing 3’ end to start synthesis; Primase
provides this via an RNA primer.
5. According to Chargaff’s rules, if a DNA sample contains 20% Adenine, what is
the percentage of Guanine?
A. 20%
B. 80%
C. 30%
D. 40%
Answer: C
Rationale: If A=20%, then T=20% (Total 40%). The remaining 60% must be split equally
between G and C, so G=30%.
, 6. Which process involves making an RNA copy of a DNA sequence?
A. Transcription
B. Replication
C. Translation
D. Mutation
Answer: A
Rationale: Transcription is the synthesis of RNA from a DNA template.
7. Which type of RNA carries the genetic code from the nucleus to the
ribosome?
A. tRNA
B. rRNA
C. mRNA
D. snRNA
Answer: C
Rationale: mRNA (messenger RNA) serves as the intermediate between DNA and protein
synthesis.
8. What is the function of the TATA box in eukaryotes?
A. It is a stop signal for translation
B. It acts as a promoter sequence for transcription
C. It marks the start of an intron
D. It binds to the tRNA anticodon
Answer: B
Rationale: The TATA box is a DNA sequence that indicates where a genetic sequence can
be read and decoded, helping position RNA polymerase.
