Microbiology with Lab: Week 5 - Microbial Genetics and
Biotechnology 2026 |WGU
1. Which enzyme is responsible for relaxing the supercoiling of DNA ahead of
the replication fork?
A. DNA Ligase
B. DNA Polymerase III
C. DNA Gyrase (Topoisomerase)
D. Helicase
Answer: C
Rationale: DNA Gyrase or Topoisomerase helps relieve the tension and supercoiling
created when the DNA helix is unwound.
2. In DNA replication, which enzyme is responsible for synthesizing a short RNA
sequence to provide a 3’-OH group?
A. RNA Polymerase
B. Primase
C. DNA Polymerase I
D. Helicase
Answer: B
Rationale: Primase synthesizes an RNA primer that provides the necessary 3’-OH group
for DNA polymerase to begin adding nucleotides.
,3. DNA replication is described as ‘semiconservative’ because:
A. The entire original molecule is kept intact.
B. Only half of the DNA is copied during each cycle.
C. Each new DNA molecule consists of one original strand and one newly synthesized strand.
D. The two strands of the double helix are identical.
Answer: C
Rationale: Semiconservative replication means each daughter DNA molecule contains one
conserved strand from the parent and one new strand.
4. Which enzyme joins Okazaki fragments together on the lagging strand?
A. DNA Polymerase III
B. Primase
C. DNA Ligase
D. RNA Polymerase
Answer: C
Rationale: DNA Ligase creates phosphodiester bonds between the sugar-phosphate
backbones of DNA fragments.
5. In which direction is a new DNA strand always synthesized?
A. 3’ to 5’
B. 5’ to 3’
C. Left to right
D. Bidirectionally
Answer: B
Rationale: DNA polymerase can only add nucleotides to the 3’ end of a growing strand,
meaning synthesis occurs in the 5’ to 3’ direction.
, 6. What is the primary function of DNA Polymerase I in E. coli?
A. Unwinding the DNA helix
B. Removing RNA primers and filling the gaps with DNA
C. Synthesizing the majority of the new DNA
D. Repairing damaged DNA during UV exposure
Answer: B
Rationale: DNA Polymerase I removes the RNA primers used during replication and
replaces them with DNA nucleotides.
7. Transcription begins when RNA polymerase binds to a specific DNA sequence
called the:
A. Promoter
B. Codon
C. Origin
D. Operator
Answer: A
Rationale: The promoter is the specific sequence on the DNA template where RNA
polymerase attaches to initiate transcription.
8. Which type of RNA carries the genetic information from the DNA to the
ribosome?
A. rRNA
B. mRNA
C. tRNA
D. snRNA
Answer: B
Rationale: Messenger RNA (mRNA) acts as the bridge between the genetic code in DNA
and the protein synthesis machinery.
Biotechnology 2026 |WGU
1. Which enzyme is responsible for relaxing the supercoiling of DNA ahead of
the replication fork?
A. DNA Ligase
B. DNA Polymerase III
C. DNA Gyrase (Topoisomerase)
D. Helicase
Answer: C
Rationale: DNA Gyrase or Topoisomerase helps relieve the tension and supercoiling
created when the DNA helix is unwound.
2. In DNA replication, which enzyme is responsible for synthesizing a short RNA
sequence to provide a 3’-OH group?
A. RNA Polymerase
B. Primase
C. DNA Polymerase I
D. Helicase
Answer: B
Rationale: Primase synthesizes an RNA primer that provides the necessary 3’-OH group
for DNA polymerase to begin adding nucleotides.
,3. DNA replication is described as ‘semiconservative’ because:
A. The entire original molecule is kept intact.
B. Only half of the DNA is copied during each cycle.
C. Each new DNA molecule consists of one original strand and one newly synthesized strand.
D. The two strands of the double helix are identical.
Answer: C
Rationale: Semiconservative replication means each daughter DNA molecule contains one
conserved strand from the parent and one new strand.
4. Which enzyme joins Okazaki fragments together on the lagging strand?
A. DNA Polymerase III
B. Primase
C. DNA Ligase
D. RNA Polymerase
Answer: C
Rationale: DNA Ligase creates phosphodiester bonds between the sugar-phosphate
backbones of DNA fragments.
5. In which direction is a new DNA strand always synthesized?
A. 3’ to 5’
B. 5’ to 3’
C. Left to right
D. Bidirectionally
Answer: B
Rationale: DNA polymerase can only add nucleotides to the 3’ end of a growing strand,
meaning synthesis occurs in the 5’ to 3’ direction.
, 6. What is the primary function of DNA Polymerase I in E. coli?
A. Unwinding the DNA helix
B. Removing RNA primers and filling the gaps with DNA
C. Synthesizing the majority of the new DNA
D. Repairing damaged DNA during UV exposure
Answer: B
Rationale: DNA Polymerase I removes the RNA primers used during replication and
replaces them with DNA nucleotides.
7. Transcription begins when RNA polymerase binds to a specific DNA sequence
called the:
A. Promoter
B. Codon
C. Origin
D. Operator
Answer: A
Rationale: The promoter is the specific sequence on the DNA template where RNA
polymerase attaches to initiate transcription.
8. Which type of RNA carries the genetic information from the DNA to the
ribosome?
A. rRNA
B. mRNA
C. tRNA
D. snRNA
Answer: B
Rationale: Messenger RNA (mRNA) acts as the bridge between the genetic code in DNA
and the protein synthesis machinery.
