DNA Synthesis
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Questions and Answers

Which direction does the leading strand grow in DNA replication?

  • 5' to 3' (correct)
  • 3' to 5'
  • Both 5' to 3' and 3' to 5'
  • None of the above

    • What is the direction of growth of the lagging strand in DNA replication?

  • 5' to 3'
  • 3' to 5' (correct)
  • Both 5' to 3' and 3' to 5'
  • None of the above

    • How are Okazaki fragments joined together in DNA replication?

  • By helicase
  • By DNA ligase (correct)
  • By DNA polymerase I
  • By DNA polymerase III

    • Which model describes the synthesis of the lagging strand in DNA replication?

    <p>Trombone model</p> Signup and view all the answers

    What is the role of DNA polymerase I in DNA replication?

    <p>It removes the RNA primer</p> Signup and view all the answers

    Which DNA repair mechanism is responsible for removing larger mutations that distort DNA structure?

    <p>Nucleotide excision repair</p> Signup and view all the answers

    What is the function of the Telomerase enzyme in DNA replication?

    <p>It maintains telomeric length</p> Signup and view all the answers

    Which enzyme is responsible for unwinding the double helix during DNA replication?

    <p>DNA helicase</p> Signup and view all the answers

    Which type of DNA repair process is used to correct DNA mutations caused by exposure to UV radiation?

    <p>Nucleotide excision repair</p> Signup and view all the answers

    During DNA replication, in which direction is the leading strand synthesized?

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

    Which protein is responsible for binding to the single-stranded DNA created by DNA helicase during DNA replication?

    <p>Single-stranded binding (SSB) proteins</p> Signup and view all the answers

    Which enzyme is responsible for synthesizing a short RNA primer during DNA replication?

    <p>Primase</p> Signup and view all the answers

    Which type of DNA repair process is used to correct DNA mutations caused by errors during DNA replication?

    <p>Mismatch repair</p> Signup and view all the answers

    Which enzyme is responsible for removing RNA primers and replacing them with DNA during DNA replication?

    <p>DNA polymerase I</p> Signup and view all the answers

    Which repair pathway requires sister chromatids and occurs during S and G2 phase?

    <p>Homologous Recombination</p> Signup and view all the answers

    Which repair pathway is used by post mitotic cells and cycling cells in G1?

    <p>Non-homologous End-Joining</p> Signup and view all the answers

    Which repair pathway involves removing altered bases, removing the phosphoribose backbone, filling in the gap, and sealing the strand?

    <p>Base Excision Repair</p> Signup and view all the answers

    Which repair pathway uses a repair template and requires sister chromatids?

    <p>Homologous Recombination</p> Signup and view all the answers

    Which repair pathway does not use a repair template and directly ligates broken ends?

    <p>Non-homologous End-Joining</p> Signup and view all the answers

    Which repair pathway recognizes mis-incorporated bases, removes them, and replaces them with the correct bases?

    <p>Mismatch repair</p> Signup and view all the answers

    Which repair pathway removes incorrect bases with a few surrounding bases and replaces them with the correct bases?

    <p>Base Excision Repair</p> Signup and view all the answers

    Which repair pathway is responsible for repairing DNA double strand breaks?

    <p>Homologous Recombination</p> Signup and view all the answers

    Which repair pathway binds to the double stranded break and recruits necessary polymerase and ligase to repair the break?

    <p>Non-homologous End-Joining</p> Signup and view all the answers

    Which type of DNA mutation involves the substitution of a single base?

    <p>Point mutation</p> Signup and view all the answers

    Which repair process is responsible for correcting base-pairing errors?

    <p>Mismatch repair</p> Signup and view all the answers

    Which repair process is used to fix bulky lesions caused by UV radiation?

    <p>Nucleotide excision repair</p> Signup and view all the answers

    Which repair process involves the removal of RNA primers and their replacement with DNA during DNA replication?

    <p>Base excision repair</p> Signup and view all the answers

    Which type of DNA mutation involves the addition of extra bases?

    <p>Insertion</p> Signup and view all the answers

    Which repair process involves the joining of Okazaki fragments in DNA replication?

    <p>Double-strand break repair</p> Signup and view all the answers

    Which repair process does not use a repair template and directly ligates broken ends?

    <p>Double-strand break repair</p> Signup and view all the answers

    Which repair process is used to correct DNA mutations caused by exposure to mutagens?

    <p>Nucleotide excision repair</p> Signup and view all the answers

    Which repair process is used to correct DNA mutations caused by errors during DNA replication?

    <p>Mismatch repair</p> Signup and view all the answers

    Which repair process involves the alteration of the reading frame in DNA?

    <p>Frameshift mutation</p> Signup and view all the answers

    Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

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

    Which nitrogenous base pairs with guanine in DNA?

    <p>Cytosine</p> Signup and view all the answers

    What is the function of telomeres in eukaryotic chromosomes?

    <p>To prevent the loss of genetic material during DNA replication</p> Signup and view all the answers

    Which enzyme is responsible for unwinding the DNA double helix during DNA replication?

    <p>DNA helicase</p> Signup and view all the answers

    What are the three parts of a nucleotide in DNA?

    <p>Phosphate group, deoxyribose sugar, and nitrogenous base</p> Signup and view all the answers

    Which enzyme synthesizes RNA primers during DNA replication?

    <p>Primase</p> Signup and view all the answers

    Which nitrogenous base pairs with thymine in DNA?

    <p>Adenine</p> Signup and view all the answers

    Which enzyme builds new DNA strands during DNA replication?

    <p>DNA polymerase</p> Signup and view all the answers

    What is the structure of DNA?

    <p>Double-stranded helix</p> Signup and view all the answers

    Which nitrogenous base pairs with adenine in DNA?

    <p>Thymine</p> Signup and view all the answers

    Which enzyme is responsible for unwinding the DNA double helix during DNA replication?

    <p>Helicase</p> Signup and view all the answers

    What is the function of telomeres in eukaryotic chromosomes?

    <p>To prevent the loss of genetic information</p> Signup and view all the answers

    Which enzyme builds new DNA strands during DNA replication?

    <p>DNA polymerase</p> Signup and view all the answers

    Which repair pathway involves removing altered bases, removing the phosphoribose backbone, filling in the gap, and sealing the strand?

    <p>Base excision repair</p> Signup and view all the answers

    During DNA replication, in which direction is the leading strand synthesized?

    <p>5'-to-3'</p> Signup and view all the answers

    Which nitrogenous base pairs with adenine in DNA?

    <p>Thymine</p> Signup and view all the answers

    Which type of DNA mutation involves the substitution of a single base?

    <p>Point mutation</p> Signup and view all the answers

    Which enzyme is responsible for synthesizing a short RNA primer during DNA replication?

    <p>Primase</p> Signup and view all the answers

    Which repair pathway is responsible for removing incorrect bases with a few surrounding bases and replacing them with the correct bases?

    <p>Mismatch repair</p> Signup and view all the answers

    What is the primary function of telomerase in DNA replication?

    <p>To synthesize the ends of linear chromosomes</p> Signup and view all the answers

    Which repair pathway is used to fix larger mutations that distort DNA structure?

    <p>Nucleotide excision repair</p> Signup and view all the answers

    Which repair pathway is responsible for repairing DNA double strand breaks?

    <p>DNA non-homologous end-joining (NHEJ)</p> Signup and view all the answers

    What is the role of error checking and repair systems in maintaining the integrity of the genome?

    <p>To repair DNA damage</p> Signup and view all the answers

    Study Notes

    DNA Replication and Structure

    • The leading strand grows continuously in the 5' to 3' direction during DNA replication.
    • The lagging strand is synthesized discontinuously in short fragments, known as Okazaki fragments, in the 3' to 5' direction.
    • Okazaki fragments are joined together by the enzyme DNA ligase.
    • The lagging strand synthesis model is described by the discontinuous replication model.

    Enzymatic Roles in DNA Replication

    • DNA polymerase I is responsible for removing RNA primers and replacing them with DNA.
    • DNA helicase unwinds the double helix structure of DNA, creating single-stranded DNA.
    • RNA primase synthesizes short RNA primers required for DNA synthesis.
    • DNA polymerase synthesizes new DNA strands and builds in the 5' to 3' direction.
    • Telomerase adds repetitive sequences to the ends of chromosomes to prevent degradation.

    DNA Repair Mechanisms

    • Nucleotide excision repair (NER) corrects larger mutations that distort DNA structure, often caused by UV radiation.
    • Base excision repair (BER) involves the removal of altered bases and the phosphoribose backbone, filling in the resultant gap, and sealing the strand.
    • Homologous recombination (HR) requires sister chromatids for accurate repair and occurs during the S and G2 phases of the cell cycle.
    • Non-homologous end joining (NHEJ) does not require a repair template, directly ligating broken ends together.
    • Mismatch repair (MMR) recognizes mis-incorporated bases, removes them, and replaces them with the correct ones.
    • The proofreading function serves to correct base-pairing errors and improve fidelity.

    Types of DNA Mutations

    • Point mutation involves the substitution of a single base pair.
    • Insertion mutation reflects the addition of extra bases, altering reading frames.
    • Telomeres, located at the ends of eukaryotic chromosomes, protect against degradation and ensure chromosome stability.

    Summary of Key Enzymes and Their Functions

    • DNA polymerase: Main enzyme responsible for synthesizing new DNA strands.
    • DNA ligase: Joins Okazaki fragments on the lagging strand during replication.
    • DNA helicase: Unwinds the double-stranded DNA helix.
    • RNA primase: Synthesizes RNA primers to initiate replication.

    Nitrogenous Base Pairing

    • Guanine pairs with cytosine.
    • Adenine pairs with thymine.

    Nucleotide Structure

    • Nucleotides consist of a nitrogenous base, a sugar (deoxyribose in DNA), and a phosphate group.

    Error Checking and Repair Systems

    • Error checking and repair systems are crucial for maintaining genomic integrity, correcting errors during DNA replication, and preventing mutation accumulation.

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    Related Documents

    DNA Synthesis - Ch 30 (Fall 2023) PDF

    Description

    Test your knowledge on DNA replication with this informative quiz! Learn about the process of elongation, the directions of growth for the leading and lagging strands, and the role of ligase in joining Okazaki fragments. Don't miss out on understanding the trombone model for lagging strand synthesis as well.

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