DNA Replication Overview
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Questions and Answers

What role does DNA polymerase I play in DNA replication?

  • It seals the gaps between okazaki fragments.
  • It synthesizes new RNA primers.
  • It removes RNA primers and replaces them with DNA. (correct)
  • It acts as a proofreading enzyme for both strands.

    • What is the function of the 3’ to 5’ exonuclease activity of DNA polymerases?

  • It synthesizes new RNA primers.
  • It removes the RNA primer from the newly formed DNA.
  • It facilitates the joining of okazaki fragments.
  • It proofreads and corrects errors during DNA synthesis. (correct)

    • How are okazaki fragments connected during DNA replication?

  • By DNA polymerase III.
  • By the formation of phosphodiester bonds by DNA ligase. (correct)
  • By transient hydrogen bonds.
  • By ligating RNA primers.

    • During the replication process, what leads to the possibility of mutations?

    <p>Errors during the replication process.</p> Signup and view all the answers

    What is the correct order of actions taken by DNA polymerase I during replication?

    <p>Remove the RNA primer, proofread, seal the gap</p> Signup and view all the answers

    What is the role of specific initiation proteins in DNA replication?

    <p>They recognize the initiation site on DNA.</p> Signup and view all the answers

    What is the significance of RNA primer in DNA replication?

    <p>It serves as a starting point for DNA synthesis.</p> Signup and view all the answers

    In which direction does DNA polymerase III add nucleotides during DNA synthesis?

    <p>5’ to 3’ direction</p> Signup and view all the answers

    What characterizes the leading strand during DNA replication?

    <p>It is continuously synthesized.</p> Signup and view all the answers

    What distinguishes Okazaki fragments in DNA replication?

    <p>They are small segments synthesized discontinuously.</p> Signup and view all the answers

    Which enzyme is responsible for sealing the gaps formed after RNA primers are removed?

    <p>Polynucleotide ligase</p> Signup and view all the answers

    What is the function of unwinding proteins in DNA replication?

    <p>They assist in separating the DNA strands.</p> Signup and view all the answers

    How does the activity of DNA polymerase III differ on the leading and lagging strands?

    <p>It synthesizes continuously on the leading strand but in fragments on the lagging strand.</p> Signup and view all the answers

    Study Notes

    DNA Replication: A Detailed Overview

    • Initiation: Replication begins at specific sites called origins. These origins are 100-200 base pair sequences recognized by initiation proteins. RNA polymerase synthesizes RNA primers which are required to begin DNA chain formation. Prokaryotes usually have one origin, while eukaryotes have multiple.
    • Unwinding: DNA unwinding proteins attach to the nicked DNA, separating the double helix.
    • Template DNA: The original DNA strand serves as a template for the new strand synthesis.
    • RNA Primer: RNA primers are essential for initiating DNA synthesis. Without them, replication is unstable.
    • Chain Elongation: DNA polymerase III adds nucleotides in the 5' to 3' direction.
    • Replication Forks: The unwinding process creates replication forks (bubbles).
    • Okazaki Fragments: The lagging strand is synthesized discontinuously in short fragments (Okazaki fragments). This is because DNA polymerase III can only synthesize in the 5' to 3' direction. The leading strand is synthesized continuously.
    • Ligation: RNA primers are removed, and the gaps are sealed by DNA ligase.
    • Bidirectional vs. Unidirectional: Replication can occur in one direction (unidirectional) or in both directions (bidirectional) from the origin.
    • Proofreading: DNA polymerase I and III have proofreading features (3' to 5' exonuclease activity) to correct errors during replication.
    • Primer Removal and Completion: DNA polymerase I removes RNA primers and replaces them with DNA.
    • Fragment Joining: DNA ligase creates phosphodiester bonds between Okazaki fragments, completing the lagging strand.

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    Description

    Explore the intricate process of DNA replication in this quiz. From initiation at specific origins to the synthesis of Okazaki fragments, test your knowledge on each step involved in this essential biological process. Perfect for students studying molecular biology and genetics.

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