MBG307: The Cell Cycle - Course Syllabus Overview Quiz
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Questions and Answers

What is the role of protein kinases ATR and ATM in the DNA damage response?

  • Decreased expression of genes promoting apoptosis
  • Activation of Chk1 and Chk2 (correct)
  • Inhibition of DNA repair enzymes
  • Promotion of cell cycle progression

    • What is the result of p53 activation during the DNA damage response?

  • Inhibition of DNA repair enzymes
  • Promotion of cell cycle progression
  • Decreased expression of genes promoting apoptosis
  • Increased expression of genes promoting long-term cell-cycle arrest or apoptosis (correct)

    • Which statement accurately describes the effect of nucleotide damage?

  • Promotion of DNA repair enzymes
  • Promotion of cell cycle progression
  • Inhibition of Chk1 and Chk2 activation
  • Loss of the base from purine nucleotides (correct)

    • What is the function of Chk1 and Chk2 in the DNA damage response?

    <p>Triggering increased expression of genes encoding DNA repair enzymes</p> Signup and view all the answers

    What is the role of protein kinases ATR and ATM in the DNA damage response?

    <p>Activation of Chk1 and Chk2</p> Signup and view all the answers

    What is the result of p53 activation during the DNA damage response?

    <p>Increased expression of genes promoting long-term cell-cycle arrest or apoptosis</p> Signup and view all the answers

    What is the name of the repair mechanism used to remove and replace bulky lesions in the DNA?

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

    Which protein kinase is specialized for the response to double-strand breaks?

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

    What does ATR specifically recognize to trigger a damage response?

    <p>Single-stranded DNA</p> Signup and view all the answers

    In which phase is the cell generally more sensitive to DNA damage?

    <p>S phase</p> Signup and view all the answers

    What is the result of a mutation in the gene for ATM in humans?

    <p>Reduced ability to repair radiation-induced double-strand breaks and an increased risk of developing cancer</p> Signup and view all the answers

    What is the name of the protein that coats single-stranded DNA and is important for DNA replication?

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

    Which enzyme completes the repair after a damaged base is removed from the DNA backbone in base excision repair?

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

    What is required for the response to many different forms of DNA damage?

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

    What triggers little or no ATR response when it occurs in G1 phase but activates ATR during S phase?

    <p>$\gamma$-radiation damage</p> Signup and view all the answers

    Which mechanism is used to remove and replace a damaged base using the undamaged strand as a template?

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

    During the DNA damage response, what is the role of protein kinases ATR and ATM?

    <p>Triggering increased expression of genes encoding DNA repair enzymes</p> Signup and view all the answers

    Which enzymes are recruited to the damaged site during the DNA damage response?

    <p>Protein kinases ATR or ATM</p> Signup and view all the answers

    What is the result of p53 activation during the DNA damage response?

    <p>Increased expression of genes promoting long-term cell-cycle arrest or apoptosis</p> Signup and view all the answers

    Which phase is the cell generally more sensitive to DNA damage?

    <p>S phase</p> Signup and view all the answers

    What triggers little or no ATR response when it occurs in G1 phase but activates ATR during S phase?

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

    What is required for the response to many different forms of DNA damage?

    <p>Protein kinases ATR or ATM</p> Signup and view all the answers

    What is the role of the protein kinases ATR and ATM in the DNA damage response?

    <p>They are specialized for the response to different forms of DNA damage, with ATR recognizing single-stranded DNA and ATM specialized for double-strand breaks.</p> Signup and view all the answers

    What triggers little or no ATR response when it occurs in G1 phase but activates ATR during S phase?

    <p>Methylation and UV-induced thymine dimers</p> Signup and view all the answers

    Which enzyme completes the repair after a damaged base is removed from the DNA backbone in base excision repair?

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

    During the DNA damage response, what is the role of protein kinases ATR and ATM?

    <p>They recruit one or both of the protein kinases CHK1 and CHK2 to the site of damage.</p> Signup and view all the answers

    Which statement accurately describes the effect of nucleotide damage?

    <p>Nucleotide damage stimulates an extensive ATR response during S phase due to delayed replication forks.</p> Signup and view all the answers

    What is required for the response to many different forms of DNA damage?

    <p>Presence of intact sister chromatids for recombinational double-strand break repair</p> Signup and view all the answers

    What does ATR specifically recognize to trigger a damage response?

    <p>Tracts of single-stranded DNA coated by RPA</p> Signup and view all the answers

    Study Notes

    DNA Damage Response: Key Proteins and Mechanisms

    • Protein kinases ATR (Ataxia Telangiectasia and Rad3-related) and ATM (Ataxia Telangiectasia Mutated) are crucial in detecting and responding to DNA damage within cells.
    • ATR primarily responds to single-strand breaks and replication stress, while ATM is specialized for double-strand breaks caused by ionizing radiation or other severe DNA damage.
    • Upon activation, ATM phosphorylates key substrates, including p53, which is a critical tumor suppressor involved in cell cycle regulation and apoptosis.

    Role of p53 Activation

    • p53 activation leads to cell cycle arrest, allowing time for DNA repair mechanisms to function effectively.
    • In case of irreparable damage, p53 can trigger apoptosis, preventing the propagation of damaged genetic material.

    Nucleotide Damage Effects

    • Nucleotide damage can result in mutations, genomic instability, and contribute to the development of cancer and other diseases if not properly repaired.

    Function of Checkpoint Kinases

    • Chk1 and Chk2 are checkpoint kinases activated by ATR and ATM, respectively; they help coordinate the cell cycle with DNA repair processes.
    • Chk1 is particularly responsive to single-strand breaks and replication stress, while Chk2 responds to double-strand breaks.

    DNA Repair Mechanisms

    • Nucleotide excision repair (NER) is the mechanism used to remove and replace bulky lesions in DNA.
    • Base excision repair (BER) involves the removal of damaged bases and can be completed by DNA polymerase after the damaged base is excised.

    Sensitivity to DNA Damage

    • Cells are generally more sensitive to DNA damage during the S phase of the cell cycle, as this is when DNA replication occurs, increasing the risk of lesions.

    Consequences of ATM Mutation

    • A mutation in the ATM gene in humans is associated with Ataxia Telangiectasia, a disorder characterized by neurodegenerative symptoms and increased cancer susceptibility.

    Key Proteins in DNA Repair

    • Replication protein A (RPA) coats single-stranded DNA and is crucial for DNA replication and repair processes.
    • DNA ligase completes the repair by sealing nicks in the DNA backbone during base excision repair.

    ATR Specific Recognition

    • ATR specifically recognizes single-strand DNA (ssDNA) regions, particularly those that arise during replication stress or nucleotide excision processes.

    General Requirements for DNA Damage Response

    • The DNA damage response involves various proteins and mechanisms to address multiple forms of DNA damage, including BRCA1 and RAD51, which play roles in homologous recombination repair.

    Activation Triggers of ATR

    • The presence of ssDNA in S phase leads to a strong ATR activation, while it triggers little or no response in G1 phase, where the DNA is generally more intact.

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    Description

    Test your knowledge on the overview of the eukaryotic cell cycle, model organisms in cell cycle analysis, cell cycle control system, CDKs and cyclins, mitosis, the mitotic spindle, cytokinesis, cell proliferation, growth, and DNA damage response. This quiz covers the syllabus for the 2022-2023 Fall Semester of MBG307 course on The Cell Cycle.

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