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Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 11 - Gene Mutation, DNA Repair, and Homologous RecombinationProblem 13b
Chapter 11, Problem 13b

Answer the following questions concerning the accuracy of DNA polymerase during replication.
If a DNA replication error is detected by DNA polymerase, how is it corrected?

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DNA polymerase has a proofreading function that helps maintain the accuracy of DNA replication. This function is carried out by its 3' to 5' exonuclease activity.
When DNA polymerase incorporates an incorrect nucleotide during replication, the enzyme detects the mismatch due to improper base pairing.
The 3' to 5' exonuclease activity of DNA polymerase removes the incorrectly paired nucleotide from the newly synthesized strand.
After the incorrect nucleotide is removed, DNA polymerase resumes synthesis by adding the correct nucleotide to the growing strand.
This proofreading mechanism significantly reduces the error rate during DNA replication, ensuring high fidelity in the process.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

DNA Polymerase Function

DNA polymerase is an enzyme responsible for synthesizing new DNA strands by adding nucleotides complementary to the template strand during replication. It plays a crucial role in ensuring the accuracy of DNA replication by proofreading the newly synthesized DNA.
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Proofreading Mechanism

DNA polymerase has a built-in proofreading ability that allows it to detect and correct errors in the DNA sequence. When an incorrect nucleotide is incorporated, the enzyme can reverse its activity, excise the erroneous nucleotide, and replace it with the correct one, thus maintaining fidelity during DNA replication.
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Proofreading

Mismatch Repair System

In addition to the proofreading function of DNA polymerase, cells have a mismatch repair system that identifies and repairs any remaining errors after replication. This system involves several proteins that recognize mismatched base pairs, excise the incorrect segment, and fill in the gap with the correct nucleotides, further enhancing the accuracy of DNA replication.
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Related Practice
Textbook Question

Two different mutations are identified in a haploid strain of yeast. The first prevents the synthesis of adenine by a nonsense mutation of the ade-1 gene. In this mutation, a base-pair substitution changes a tryptophan codon (UGG) to a stop codon (UGA). The second affects one of several duplicate tRNA genes. This base-pair substitution mutation changes the anticodon sequence of a tRNAᵀʳᵖ from


   3′−ACC−5′ to 3′−ACU−5′


Assuming there are no other mutations in the genome, will this double-mutant yeast strain be able to grow on minimal medium? If growth will occur, characterize the nature of growth relative to wild type.

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Textbook Question

What is the phenotypic effect of inserting a Ds element into the maize C gene? How do Ds and Ac produce maize kernels that are mostly yellow with purple spots?

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Textbook Question

Answer the following questions concerning the accuracy of DNA polymerase during replication.

What general mechanism do DNA polymerases use to check the accuracy of DNA replication and identify errors during replication?

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Textbook Question

Answer the following questions concerning the accuracy of DNA polymerase during replication.

If a replication error escapes detection and correction, what kind of abnormality is most likely to exist at the site of the replication error?

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Textbook Question

Answer the following questions concerning the accuracy of DNA polymerase during replication.

Identify two mechanisms that can correct the kind of abnormality resulting from the circumstances identified in part (c).

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Textbook Question

Answer the following questions concerning the accuracy of DNA polymerase during replication.

If the kind of abnormality identified in part (c) is not corrected before the next DNA replication cycle, what kind of mutation occurs?

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