BIOD 102 Exam 1: 100 Questions & Answers: Latest Updated A+ Score
Guide
Molecular Genetics: DNA Replication and Protein Synthesis
1. True or False:
Replication of DNA begins at a single origin of replication and proceeds
the entire length of the strand in one direction.
A) True
B) False Answer
: B Rationale: DNA replication begins at multiple origins of replication along
the helix, not a single origin.
2. Which enzyme is responsible for relieving the tension caused by the twisting
and untwisting of the DNA strand during replication?
A) Helicase
B) Topoisomerase
C) DNA Polymerase
D) Primase Answer: B Rationale: Topoisomerase functions to relieve strain in the
double helix ahead of the replication fork by breaking and rejoining DNA strands.
3. What is the primary function of DNA polymerase during the elongation of a
replicated DNA strand?
A) Untwisting the double helix
B) Adding nucleotides to the growing strand
,C) Relieving twisting stress
D) Synthesizing RNA primers
Answer: B Rationale:
DNA polymerase is the enzyme responsible for adding nucleotides to a growing
DNA chain.
4. Where does the energy required to add a nucleotide to a growing DNA chain
come from?
A) Hydrolysis of the nucleotide’s pyrophosphate tail
B) ATP from the mitochondria
C) The breakdown of glucose
D) Solar energy
Answer: A Rationale: Adding a nucleotide is an endergonic process powered by
the exergonic reaction of hydrolyzing the nucleotide's own pyrophosphate tail.
5. In which direction are new nucleotides added to the leading strand during
elongation?
A) 3’ to 5’
B) 5’ to 3’
C) Both directions
D) Randomly
, Answer: B Rationale: DNA and RNA synthesis always occur in the 5’ to 3’
direction.
6. How many RNA primers are required for the leading strand versus the lagging
strand?
A) Leading: many; Lagging: one
B) Leading: none; Lagging: many
C) Leading: one; Lagging: more than one
D) Leading: two; Lagging: two
Answer: C Rationale: The leading strand is synthesized continuously and requires
only one primer, while the lagging strand is synthesized in fragments (Okazaki
fragments), each requiring its own primer.
7. Which enzyme is responsible for replacing RNA nucleotides with DNA
nucleotides in a newly synthesized strand?
A) DNA Ligase
B) Helicase
C) DNA Polymerase
D) Primase
Answer: C
Rationale: DNA polymerase removes RNA primers and replaces them with the
appropriate DNA nucleotides.
Guide
Molecular Genetics: DNA Replication and Protein Synthesis
1. True or False:
Replication of DNA begins at a single origin of replication and proceeds
the entire length of the strand in one direction.
A) True
B) False Answer
: B Rationale: DNA replication begins at multiple origins of replication along
the helix, not a single origin.
2. Which enzyme is responsible for relieving the tension caused by the twisting
and untwisting of the DNA strand during replication?
A) Helicase
B) Topoisomerase
C) DNA Polymerase
D) Primase Answer: B Rationale: Topoisomerase functions to relieve strain in the
double helix ahead of the replication fork by breaking and rejoining DNA strands.
3. What is the primary function of DNA polymerase during the elongation of a
replicated DNA strand?
A) Untwisting the double helix
B) Adding nucleotides to the growing strand
,C) Relieving twisting stress
D) Synthesizing RNA primers
Answer: B Rationale:
DNA polymerase is the enzyme responsible for adding nucleotides to a growing
DNA chain.
4. Where does the energy required to add a nucleotide to a growing DNA chain
come from?
A) Hydrolysis of the nucleotide’s pyrophosphate tail
B) ATP from the mitochondria
C) The breakdown of glucose
D) Solar energy
Answer: A Rationale: Adding a nucleotide is an endergonic process powered by
the exergonic reaction of hydrolyzing the nucleotide's own pyrophosphate tail.
5. In which direction are new nucleotides added to the leading strand during
elongation?
A) 3’ to 5’
B) 5’ to 3’
C) Both directions
D) Randomly
, Answer: B Rationale: DNA and RNA synthesis always occur in the 5’ to 3’
direction.
6. How many RNA primers are required for the leading strand versus the lagging
strand?
A) Leading: many; Lagging: one
B) Leading: none; Lagging: many
C) Leading: one; Lagging: more than one
D) Leading: two; Lagging: two
Answer: C Rationale: The leading strand is synthesized continuously and requires
only one primer, while the lagging strand is synthesized in fragments (Okazaki
fragments), each requiring its own primer.
7. Which enzyme is responsible for replacing RNA nucleotides with DNA
nucleotides in a newly synthesized strand?
A) DNA Ligase
B) Helicase
C) DNA Polymerase
D) Primase
Answer: C
Rationale: DNA polymerase removes RNA primers and replaces them with the
appropriate DNA nucleotides.
