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Cell Cycle Regulation quiz #2

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  • What is the purpose of checkpoints in the cell cycle?
    Checkpoints in the cell cycle ensure proper cell division by verifying DNA integrity, confirming accurate DNA replication, ensuring necessary proteins for mitosis are present, and checking chromosome alignment during metaphase.
  • What does the G1 checkpoint check?
    The G1 checkpoint checks for DNA integrity before replication, ensuring there are no errors in the DNA.
  • What is necessary for a cell to pass the G2 checkpoint?
    For a cell to pass the G2 checkpoint, it must have all the necessary enzymes and proteins required for mitosis and cytokinesis.
  • What enzymes control the progression of cells through the cell cycle checkpoints?
    Cyclins and cyclin-dependent kinases (CDKs) control the progression of cells through the cell cycle checkpoints.
  • How is the cell cycle regulated?
    The cell cycle is regulated by checkpoints that act as stop signs, ensuring the cell does not prematurely enter the next phase and that errors are corrected.
  • Which factors can disrupt the cell cycle?
    Factors such as DNA damage, lack of growth factors, and improper chromosome alignment can disrupt the cell cycle.
  • What is the second part of the cell theory?
    The second part of the cell theory states that all living organisms are composed of cells.
  • Which factors determine whether a cell enters G0?
    Factors such as nutrient availability, growth signals, and cell type determine whether a cell enters G0.
  • Many of the negative regulator proteins of the cell cycle were discovered in what type of cells?
    Many negative regulator proteins of the cell cycle were discovered in cancer cells.
  • Which is not part of the cell theory?
    The idea that cells can spontaneously generate is not part of the cell theory.
  • What controls the cell cycle at key checkpoints?
    The cell cycle is controlled at key checkpoints by cyclins and cyclin-dependent kinases (CDKs).
  • What are cell cycle regulators?
    Cell cycle regulators are proteins that control the progression of the cell cycle, including cyclins, CDKs, and checkpoint proteins.
  • At which of the cell-cycle checkpoints do external forces have the greatest influence?
    External forces have the greatest influence at the G1 checkpoint.
  • What occurs at the G1 checkpoint?
    At the G1 checkpoint, the cell checks for DNA integrity and repairs any damage before proceeding to DNA replication.
  • What are 2 examples of proteins involved in positive regulation of the cell cycle?
    Cyclins and cyclin-dependent kinases (CDKs) are examples of proteins involved in positive regulation of the cell cycle.
  • What type of protein that regulates the cell cycle is encoded by proto-oncogenes?
    Proto-oncogenes encode proteins that promote cell cycle progression, such as growth factors and cyclins.
  • At what stage of the cell cycle is the cyclin component of MPF destroyed?
    The cyclin component of MPF is destroyed during the transition from metaphase to anaphase.
  • A cell has damaged DNA. Which checkpoint is responsible for checking this?
    The G1 checkpoint is responsible for checking and repairing damaged DNA.
  • What purpose does the G2 checkpoint serve?
    The G2 checkpoint ensures that all necessary proteins and enzymes for mitosis are present and checks for DNA replication errors.
  • Which checkpoint checks that the DNA has been replicated correctly?
    The S checkpoint checks that the DNA has been replicated correctly.
  • What factors are necessary for a cell to pass the G1 checkpoint?
    DNA integrity and growth factors are necessary for a cell to pass the G1 checkpoint.
  • What is the third part of cell theory?
    The third part of cell theory states that all cells arise from pre-existing cells.
  • What explains density-dependent inhibition in cell division?
    Cells stop dividing when they touch each other.
  • Damage to DNA can halt division of the cell at which stage of the cell cycle?
    Damage to DNA can halt division at the G1 checkpoint.
  • How do cyclins and CDKs control the cell cycle?
    Cyclins and CDKs control the cell cycle by forming complexes that activate or inhibit progression through checkpoints.
  • Which checkpoint does not control the progression of the cell cycle?
    Cytokinesis checkpoint is not a checkpoint that controls the progression of the cell cycle.
  • Which of these controls each of the checkpoints that regulate cell division?
    Cyclins and cyclin-dependent kinases (CDKs) control each of the checkpoints that regulate cell division.
  • What happens if the cell passes the G1 checkpoint?
    If the cell passes the G1 checkpoint, it proceeds to the S phase for DNA replication.
  • What is the role of the p53 protein in the cell cycle in normal cells?
    The p53 protein acts as a tumor suppressor, repairing DNA damage or triggering apoptosis if the damage is irreparable.
  • Which of these checkpoints determines if cell division has occurred properly?
    The M checkpoint determines if cell division has occurred properly by checking chromosome alignment and spindle attachment.
  • Why is the DNA damage checkpoint in G1 important?
    The DNA damage checkpoint in G1 is important to prevent replication of damaged DNA, which could lead to mutations and cancer.
  • What two proteins are responsible for advancing a cell through the phases of the cell cycle?
    Cyclins and cyclin-dependent kinases (CDKs) are responsible for advancing a cell through the phases of the cell cycle.
  • What happens if a cell does not pass the checkpoint?
    If a cell does not pass a checkpoint, it may undergo repair processes or apoptosis to prevent errors from propagating.
  • Why is it important for the cell cycle to be strictly controlled?
    Strict control of the cell cycle is important to prevent errors that could lead to cancer and ensure proper cell division.
  • Which molecule triggers progression beyond the G2 checkpoint into mitosis?
    Cyclin B triggers progression beyond the G2 checkpoint into mitosis.
  • What happens to a cell if it does not pass the G2/M checkpoint?
    The cell will undergo apoptosis if it does not pass the G2/M checkpoint.
  • Why don’t cells all divide at the same rate?
    Cells don't all divide at the same rate due to differences in cell type, environmental conditions, and availability of growth factors.
  • What condition prevents cell division due to density-dependent factors?
    High cell density would prevent cell division due to density-dependent factors.
  • What is the primary function of cell cycle checkpoints?
    Cell cycle checkpoints act as control mechanisms that ensure each phase of the cell cycle is completed accurately before the cell proceeds to the next phase, preventing errors and maintaining proper cell division.