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DNA Repair quiz #2

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  • Which DNA sequence is most susceptible to damage by UV radiation?
    TTTTTTTT. UV radiation commonly causes damage by forming pyrimidine dimers, particularly thymine dimers, making sequences with consecutive thymine bases more susceptible.
  • Which process repairs DNA that has been damaged by ultraviolet radiation using visible light?
    Photoreactivation is the process that repairs DNA damaged by UV radiation using visible light.
  • What enzyme joins Okazaki fragments during DNA replication?
    DNA ligase is the enzyme that joins Okazaki fragments.
  • Why are pyrimidine dimers dangerous to the body?
    Pyrimidine dimers can disrupt DNA replication and transcription, leading to mutations that may cause diseases such as cancer.
  • Which enzyme is used to complete the joining of the two ends of the DNA?
    DNA ligase is used to complete the joining of the two ends of the DNA.
  • What protein cuts the damaged DNA strand during repair?
    Endonucleases are proteins that cut the damaged DNA strand during repair.
  • What is DNA proofreading?
    DNA proofreading is the ability of DNA polymerases to detect and correct errors during DNA replication, significantly reducing the error rate.
  • What would happen if you forgot to use ligase during DNA replication?
    If ligase is not used, the Okazaki fragments on the lagging strand would remain unjoined, leading to incomplete DNA replication.
  • If DNA ligase was nonfunctional, what would be the consequence?
    If DNA ligase was nonfunctional, the DNA strands would have gaps between Okazaki fragments, leading to incomplete and potentially unstable DNA.
  • What form of DNA damage is commonly caused by ultraviolet exposure?
    Thymine dimers. UV exposure commonly results in the formation of thymine dimers.
  • Which genetic disease affects DNA repair systems in humans?
    Xeroderma pigmentosum. This disease affects DNA repair systems, particularly nucleotide excision repair.
  • Which enzyme monitors a cell’s DNA for mutations during replication?
    DNA polymerase. DNA polymerase has proofreading abilities to monitor and correct mutations during replication.
  • What is the difference between mismatch repair and nucleotide excision repair?
    Mismatch repair corrects errors in base pairing, while nucleotide excision repair removes bulky DNA lesions like pyrimidine dimers.
  • Which enzyme seals Okazaki fragments together during DNA replication?
    DNA ligase seals Okazaki fragments together during DNA replication.
  • Which type of repair is a backup for the DNA polymerase proofreading function?
    Mismatch repair serves as a backup for the DNA polymerase proofreading function.
  • Which enzyme joins the gaps between synthesized DNA fragments of the lagging strand?
    DNA ligase joins the gaps between synthesized DNA fragments of the lagging strand.
  • What is the function of DNA ligase during DNA replication?
    Joining Okazaki fragments. DNA ligase functions to join Okazaki fragments during DNA replication.
  • Which enzyme can repair breaks to the phosphate-sugar backbone of DNA?
    DNA ligase can repair breaks to the phosphate-sugar backbone of DNA.
  • Which DNA repair system detects and corrects damaged or altered DNA bases?
    Base excision repair. This system detects and corrects damaged or altered DNA bases.
  • Which helps prevent errors in DNA replication? A) DNA ligase B) DNA polymerase proofreading C) RNA polymerase D) Ribosomes
    B) DNA polymerase proofreading helps prevent errors in DNA replication.
  • What happens when DNA self-correction breaks down? How might that be beneficial in some cases?
    When DNA self-correction breaks down, mutations can accumulate, potentially leading to diseases like cancer. However, in some cases, mutations can drive evolution and adaptation, providing beneficial traits.
  • What is the significance of DNA repair mechanisms in maintaining genetic integrity?
    DNA repair mechanisms correct errors that occur during DNA replication, preventing mutations that could lead to diseases like cancer and ensuring the stability of genetic information.
  • What can happen if DNA replication errors are not repaired?
    Unrepaired DNA replication errors can result in permanent mutations, which may cause diseases such as cancer.
  • Why is even a single base pairing error in DNA potentially significant?
    A single base pairing error can lead to a mutation that may alter the function of a gene, potentially causing significant changes or diseases.
  • How does the analogy of a typo in a resume help explain the impact of DNA mutations?
    Just as a single typo can change the meaning of a sentence, a single DNA mutation can alter genetic information and potentially lead to harmful consequences.
  • How do DNA repair mechanisms help prevent diseases such as cancer?
    By correcting replication errors and preventing mutations, DNA repair mechanisms reduce the risk of genetic changes that can lead to cancer.