C785 Biochemistry - Module 4: DNA Replication, Transcription, and
Translation Review 2026 |WGU
1. During DNA replication, which enzyme is responsible for unwinding the DNA
double helix at the replication fork?
A. DNA Polymerase
B. DNA Ligase
C. DNA Helicase
D. Topoisomerase
Answer: C
Rationale: DNA Helicase breaks the hydrogen bonds between the nitrogenous bases to
separate the strands and create a replication fork.
2. In which direction is a new DNA strand always synthesized?
A. 3’ to 5’
B. C-terminus to N-terminus
C. 5’ to 3’
D. Bi-directionally from the middle
Answer: C
Rationale: DNA polymerases can only add nucleotides to the 3’ hydroxyl group of a
growing strand, meaning synthesis always occurs in the 5’ to 3’ direction.
,3. What is the role of DNA Polymerase I in prokaryotic DNA replication?
A. Synthesizing the leading strand
B. Relieving torsional strain
C. Binding single strands to prevent re-annealing
D. Removing RNA primers and replacing them with DNA nucleotides
Answer: D
Rationale: DNA Polymerase I has 5’ to 3’ exonuclease activity which allows it to remove
RNA primers and fill the gaps with DNA.
4. Which enzyme joins Okazaki fragments together on the lagging strand?
A. Primase
B. DNA Ligase
C. DNA Polymerase III
D. Telomerase
Answer: B
Rationale: DNA Ligase catalyzes the formation of the phosphodiester bond between the
fragments to create a continuous sugar-phosphate backbone.
5. Which process describes the conversion of DNA into RNA?
A. Transcription
B. Translation
C. Replication
D. Translocation
Answer: A
Rationale: Transcription is the process by which RNA polymerase uses a DNA template to
synthesize a complementary RNA molecule.
, 6. Which base is found in RNA but NOT in DNA?
A. Adenine
B. Guanine
C. Thymine
D. Uracil
Answer: D
Rationale: RNA uses Uracil (U) instead of Thymine (T), which is found in DNA.
7. What is the specific region of DNA where RNA polymerase binds to initiate
transcription?
A. Exon
B. Promoter
C. Intron
D. Codon
Answer: B
Rationale: The promoter is a specific sequence upstream of a gene that signals the start
site for transcription and provides a binding site for RNA polymerase.
8. In eukaryotic cells, where does transcription primarily occur?
A. Cytoplasm
B. Nucleus
C. Ribosome
D. Endoplasmic Reticulum
Answer: B
Rationale: In eukaryotes, DNA is stored in the nucleus, so transcription must occur there
before the mRNA is exported to the cytoplasm.
Translation Review 2026 |WGU
1. During DNA replication, which enzyme is responsible for unwinding the DNA
double helix at the replication fork?
A. DNA Polymerase
B. DNA Ligase
C. DNA Helicase
D. Topoisomerase
Answer: C
Rationale: DNA Helicase breaks the hydrogen bonds between the nitrogenous bases to
separate the strands and create a replication fork.
2. In which direction is a new DNA strand always synthesized?
A. 3’ to 5’
B. C-terminus to N-terminus
C. 5’ to 3’
D. Bi-directionally from the middle
Answer: C
Rationale: DNA polymerases can only add nucleotides to the 3’ hydroxyl group of a
growing strand, meaning synthesis always occurs in the 5’ to 3’ direction.
,3. What is the role of DNA Polymerase I in prokaryotic DNA replication?
A. Synthesizing the leading strand
B. Relieving torsional strain
C. Binding single strands to prevent re-annealing
D. Removing RNA primers and replacing them with DNA nucleotides
Answer: D
Rationale: DNA Polymerase I has 5’ to 3’ exonuclease activity which allows it to remove
RNA primers and fill the gaps with DNA.
4. Which enzyme joins Okazaki fragments together on the lagging strand?
A. Primase
B. DNA Ligase
C. DNA Polymerase III
D. Telomerase
Answer: B
Rationale: DNA Ligase catalyzes the formation of the phosphodiester bond between the
fragments to create a continuous sugar-phosphate backbone.
5. Which process describes the conversion of DNA into RNA?
A. Transcription
B. Translation
C. Replication
D. Translocation
Answer: A
Rationale: Transcription is the process by which RNA polymerase uses a DNA template to
synthesize a complementary RNA molecule.
, 6. Which base is found in RNA but NOT in DNA?
A. Adenine
B. Guanine
C. Thymine
D. Uracil
Answer: D
Rationale: RNA uses Uracil (U) instead of Thymine (T), which is found in DNA.
7. What is the specific region of DNA where RNA polymerase binds to initiate
transcription?
A. Exon
B. Promoter
C. Intron
D. Codon
Answer: B
Rationale: The promoter is a specific sequence upstream of a gene that signals the start
site for transcription and provides a binding site for RNA polymerase.
8. In eukaryotic cells, where does transcription primarily occur?
A. Cytoplasm
B. Nucleus
C. Ribosome
D. Endoplasmic Reticulum
Answer: B
Rationale: In eukaryotes, DNA is stored in the nucleus, so transcription must occur there
before the mRNA is exported to the cytoplasm.
