The Question is from neet-botany , and it was created by the author Mr. NARESH KUMAR K

Question

Certain mutations in the DNA polymerase delta gene can lead to reduced fidelity of DNA replication.  Which of the following would be the MOST LIKELY direct consequence of such a mutation?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
 **Primary Concept**: DNA replication and fidelity
 **Related Topics**: DNA polymerase function, mutations, DNA repair
 **Prerequisites**: Understanding of DNA replication process, role of DNA polymerase in maintaining fidelity
## SOLUTION PATHWAY
**Given Information**:
  Mutations in DNA polymerase delta gene reduce replication fidelity.
  DNA polymerase delta is responsible for lagging strand synthesis during DNA replication.
**Method & Steps**:
 1. Understand the role of DNA polymerase delta.
  Reasoning: DNA polymerase delta is a crucial enzyme responsible for synthesizing the lagging strand during DNA replication. Its fidelity ensures accurate copying of the DNA template.
  Formula/Rule: None directly applicable.
 2. Analyze the consequence of reduced fidelity.
  Working: Reduced fidelity means an increased chance of incorporating incorrect nucleotides during DNA replication. This leads to mismatches and errors in the newly synthesized DNA strand.
  Key Point: Fidelity refers to the accuracy of DNA replication.
 3. Identify the most likely direct consequence.
  Result: An increased mutation rate in the newly synthesized DNA is the most direct and immediate consequence of reduced fidelity in DNA polymerase delta.
  Verification: The other options are indirect or less likely consequences. Decreased Okazaki fragment synthesis might occur but is not the primary effect. Inhibition of helicase is unrelated. Increased DNA repair is a response to increased errors, not a direct consequence of reduced polymerase fidelity.
 ## OPTION ANALYSIS
A :x: Decreased rate of Okazaki fragment synthesis is an indirect consequence, not directly caused by reduced fidelity.  Reduced fidelity affects the accuracy of nucleotide incorporation, not the speed of synthesis.
B :x: Inhibition of DNA unwinding by helicase is not a direct consequence of a mutation in the DNA polymerase delta gene. Helicase and DNA polymerase have distinct roles in replication.
C :x: Increased rate of DNA repair mechanisms is an indirect consequence.  The cell might attempt to repair the increased number of errors caused by reduced fidelity, but this is a secondary response.
D ✓: Increased mutation rate in the newly synthesized DNA is the most direct consequence. Reduced fidelity directly translates to more errors during replication, leading to a higher mutation rate.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the roles of different enzymes involved in DNA replication: Understand the distinct functions of DNA polymerase, helicase, and ligase.
  2.Focusing on indirect consequences:  Identify the immediate and most direct effect of the reduced fidelity of DNA polymerase.
 **Quick Tips**:
  1.Remember that DNA polymerase's primary role is accurate DNA synthesis. Reduced fidelity means less accuracy, directly leading to more mutations.
  2.Focus on the meaning of ‘fidelity’ in the context of DNA replication.

Mr. NARESH KUMAR K · Answer

Decreased rate of Okazaki fragment synthesis

Mr. NARESH KUMAR K · Answer

Inhibition of DNA unwinding by helicase

Mr. NARESH KUMAR K · Answer

Increased rate of DNA repair mechanisms

Mr. NARESH KUMAR K · Answer

The correct Option is "Increased mutation rate in the newly synthesized DNA"

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