Bio Beyond: Genetic Replication Questions
With Complete Solutions
Course
BioBeyond
1. What is the main enzyme responsible for DNA replication?
Answer:
DNA polymerase is the primary enzyme that synthesizes new DNA strands by adding
nucleotides to the growing chain.
It requires a primer to begin synthesis and works in the 5' to 3' direction.
2. What is the function of helicase in DNA replication?
Answer:
Helicase unwinds the DNA double helix by breaking hydrogen bonds between
complementary base pairs.
This creates a replication fork, allowing other enzymes to access the DNA strands for
replication.
3. Why is DNA replication described as "semi-conservative"?
Answer:
Each new DNA molecule consists of one original (parent) strand and one newly
synthesized (daughter) strand.
This preserves genetic information while allowing for duplication.
4. What is the role of primase in DNA replication?
Answer:
Primase synthesizes a short RNA primer, which provides a starting point for DNA
polymerase to begin adding nucleotides.
The primer is later removed and replaced with DNA by DNA polymerase I.
5. What is the difference between the leading and lagging strands?
,Answer:
The leading strand is synthesized continuously in the 5' to 3' direction toward the
replication fork.
The lagging strand is synthesized discontinuously in Okazaki fragments, moving
away from the fork.
DNA ligase later joins the fragments together.
6. What is the function of topoisomerase in DNA replication?
Answer:
Topoisomerase prevents supercoiling and tension ahead of the replication fork by
making temporary cuts in the DNA strands.
This allows the DNA to unwind smoothly without breaking.
7. What happens if DNA polymerase makes an error during replication?
Answer:
DNA polymerase has proofreading ability, meaning it can detect and correct
mismatched bases by removing the incorrect nucleotide and replacing it.
If an error is not fixed, it can lead to mutations, which may affect protein function.
8. Why do eukaryotic chromosomes have multiple origins of replication?
Answer:
Eukaryotic chromosomes are large and linear, so multiple origins of replication allow
DNA to be copied faster and efficiently.
This contrasts with prokaryotic DNA, which typically has a single origin of replication
due to its circular structure.
9. What are telomeres, and why are they important in DNA replication?
Answer:
, Telomeres are repetitive DNA sequences at the ends of eukaryotic chromosomes that
protect genes from being lost during replication.
Since the lagging strand cannot be fully replicated, telomeres prevent the progressive
shortening of important genetic material.
10. What is the function of telomerase?
Answer:
Telomerase extends the telomeres in certain cells, such as stem cells and germ cells,
preventing the loss of genetic information.
It uses an RNA template to add new nucleotide sequences to the ends of chromosomes.
Most somatic (body) cells do not express telomerase, which contributes to aging and
cell death.
11. What are Okazaki fragments, and why do they form?
Answer:
Okazaki fragments are short DNA sequences synthesized on the lagging strand during
DNA replication.
They form because DNA polymerase can only synthesize in the 5' to 3' direction, so
replication on the lagging strand is discontinuous.
DNA ligase later joins these fragments together to form a continuous strand.
12. What is the significance of the 5' and 3' ends of a DNA strand?
Answer:
The 5' (five-prime) end has a phosphate group, and the 3' (three-prime) end has a
hydroxyl (-OH) group.
DNA polymerase can only add new nucleotides to the 3' end, which dictates the
directionality of DNA synthesis (5' → 3').
13. How does replication in prokaryotes differ from eukaryotes?
Answer:
, Feature Prokaryotic Replication Eukaryotic Replication
DNA Structure Circular chromosome Linear chromosomes
Origin of Replication Single origin Multiple origins
Replication Speed Faster Slower
Telomeres? No Yes
Prokaryotes have one replication origin, while eukaryotes have multiple origins to
speed up replication.
14. What enzyme removes RNA primers from the DNA strands?
Answer:
DNA polymerase I (in prokaryotes) or RNase H (in eukaryotes) removes RNA
primers.
DNA polymerase then fills in the gaps with DNA nucleotides.
15. What role does DNA ligase play in replication?
Answer:
DNA ligase joins Okazaki fragments on the lagging strand by forming phosphodiester
bonds.
It ensures the final DNA molecule is continuous and stable.
16. Why is a replication bubble formed during DNA replication?
Answer:
A replication bubble forms when helicase unwinds the DNA at the origin of
replication.
It allows replication to proceed in both directions, speeding up the process.
17. What is the difference between leading and lagging strand synthesis?
Answer:
With Complete Solutions
Course
BioBeyond
1. What is the main enzyme responsible for DNA replication?
Answer:
DNA polymerase is the primary enzyme that synthesizes new DNA strands by adding
nucleotides to the growing chain.
It requires a primer to begin synthesis and works in the 5' to 3' direction.
2. What is the function of helicase in DNA replication?
Answer:
Helicase unwinds the DNA double helix by breaking hydrogen bonds between
complementary base pairs.
This creates a replication fork, allowing other enzymes to access the DNA strands for
replication.
3. Why is DNA replication described as "semi-conservative"?
Answer:
Each new DNA molecule consists of one original (parent) strand and one newly
synthesized (daughter) strand.
This preserves genetic information while allowing for duplication.
4. What is the role of primase in DNA replication?
Answer:
Primase synthesizes a short RNA primer, which provides a starting point for DNA
polymerase to begin adding nucleotides.
The primer is later removed and replaced with DNA by DNA polymerase I.
5. What is the difference between the leading and lagging strands?
,Answer:
The leading strand is synthesized continuously in the 5' to 3' direction toward the
replication fork.
The lagging strand is synthesized discontinuously in Okazaki fragments, moving
away from the fork.
DNA ligase later joins the fragments together.
6. What is the function of topoisomerase in DNA replication?
Answer:
Topoisomerase prevents supercoiling and tension ahead of the replication fork by
making temporary cuts in the DNA strands.
This allows the DNA to unwind smoothly without breaking.
7. What happens if DNA polymerase makes an error during replication?
Answer:
DNA polymerase has proofreading ability, meaning it can detect and correct
mismatched bases by removing the incorrect nucleotide and replacing it.
If an error is not fixed, it can lead to mutations, which may affect protein function.
8. Why do eukaryotic chromosomes have multiple origins of replication?
Answer:
Eukaryotic chromosomes are large and linear, so multiple origins of replication allow
DNA to be copied faster and efficiently.
This contrasts with prokaryotic DNA, which typically has a single origin of replication
due to its circular structure.
9. What are telomeres, and why are they important in DNA replication?
Answer:
, Telomeres are repetitive DNA sequences at the ends of eukaryotic chromosomes that
protect genes from being lost during replication.
Since the lagging strand cannot be fully replicated, telomeres prevent the progressive
shortening of important genetic material.
10. What is the function of telomerase?
Answer:
Telomerase extends the telomeres in certain cells, such as stem cells and germ cells,
preventing the loss of genetic information.
It uses an RNA template to add new nucleotide sequences to the ends of chromosomes.
Most somatic (body) cells do not express telomerase, which contributes to aging and
cell death.
11. What are Okazaki fragments, and why do they form?
Answer:
Okazaki fragments are short DNA sequences synthesized on the lagging strand during
DNA replication.
They form because DNA polymerase can only synthesize in the 5' to 3' direction, so
replication on the lagging strand is discontinuous.
DNA ligase later joins these fragments together to form a continuous strand.
12. What is the significance of the 5' and 3' ends of a DNA strand?
Answer:
The 5' (five-prime) end has a phosphate group, and the 3' (three-prime) end has a
hydroxyl (-OH) group.
DNA polymerase can only add new nucleotides to the 3' end, which dictates the
directionality of DNA synthesis (5' → 3').
13. How does replication in prokaryotes differ from eukaryotes?
Answer:
, Feature Prokaryotic Replication Eukaryotic Replication
DNA Structure Circular chromosome Linear chromosomes
Origin of Replication Single origin Multiple origins
Replication Speed Faster Slower
Telomeres? No Yes
Prokaryotes have one replication origin, while eukaryotes have multiple origins to
speed up replication.
14. What enzyme removes RNA primers from the DNA strands?
Answer:
DNA polymerase I (in prokaryotes) or RNase H (in eukaryotes) removes RNA
primers.
DNA polymerase then fills in the gaps with DNA nucleotides.
15. What role does DNA ligase play in replication?
Answer:
DNA ligase joins Okazaki fragments on the lagging strand by forming phosphodiester
bonds.
It ensures the final DNA molecule is continuous and stable.
16. Why is a replication bubble formed during DNA replication?
Answer:
A replication bubble forms when helicase unwinds the DNA at the origin of
replication.
It allows replication to proceed in both directions, speeding up the process.
17. What is the difference between leading and lagging strand synthesis?
Answer:
