Cell Cycle Regulation: p53 and RB Proteins
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Questions and Answers

What is p53 often referred to as?

  • The molecule of the year
  • The tumor suppressor gene
  • The cell cycle regulator
  • The guardian of the genome (correct)

    • What is the main function of p21?

  • To inhibit CDK (correct)
  • To activate DNA replication
  • To produce proteins that block the cell cycle
  • To bind DNA directly

    • What happens when tumor suppressor genes have a defect or loss of function?

  • The cell cycle is blocked
  • Cancer is more likely to occur (correct)
  • DNA replication is activated
  • The genome is protected

    • What percentage of tumors have a defect in p53?

    <p>Greater than 50%</p> Signup and view all the answers

    What is the role of RB protein in the cell cycle?

    <p>To regulate the cell cycle</p> Signup and view all the answers

    What is the relationship between p53 and RB?

    <p>They are both tumor suppressor genes</p> Signup and view all the answers

    What is the impact of a defect in tumor suppressor genes?

    <p>The genome is at a higher risk of mutation</p> Signup and view all the answers

    What is the significance of p53 being called 'the molecule of the year'?

    <p>It is highly important in regulating the cell cycle</p> Signup and view all the answers

    What is the main reason why RB is considered a tumor suppressor gene?

    <p>Because a defect in it can lead to retinoblastoma</p> Signup and view all the answers

    What is unique about P21 compared to other tumor suppressor genes?

    <p>It does not lead to cancer when defected</p> Signup and view all the answers

    What happens to mice that lack P21?

    <p>They gain the ability to regenerate their limbs</p> Signup and view all the answers

    Why is it important to regulate the cell cycle?

    <p>So cells can only divide when it's appropriate</p> Signup and view all the answers

    What is required for mitosis, or cell division, to happen?

    <p>A lot of energy and protein machinery</p> Signup and view all the answers

    Why do tumor suppressor genes regulate cell division?

    <p>So cells can divide only when appropriate</p> Signup and view all the answers

    Study Notes

    Cell Cycle Regulation

    • P53, a key protein, regulates the cell cycle at a higher level, earning it the nickname "guardian of the genome."
    • P53 binds DNA directly to produce proteins that block the progression of the cell cycle.
    • One of these proteins is p21, which functions to inhibit CDK, preventing DNA replication or activation of mitosis.

    Tumor Suppressor Genes

    • P53 and RB are considered tumor suppressor genes, which are essential for regulating the cell cycle.
    • Defects or mutations in these genes can lead to loss of function, increasing the risk of cancer.
    • Over 50% of tumors have a defect in p53, highlighting its importance in preventing cancer.

    P21 Function

    • P21 is unusual in that its defect does not lead to cancer, but rather allows mice to regenerate their limbs.
    • Scientists are still trying to understand the mechanisms behind p21's function.

    Importance of Tumor Suppressor Genes

    • Tumor suppressor genes are crucial for regulating the cell cycle, ensuring that cells divide only when appropriate.
    • Mitosis, or cell division, requires significant energy and protein machinery, making it essential to regulate the process accurately.

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    Description

    Learn about the higher levels of cell cycle regulation, including the role of p53, known as the 'guardian of the genome', and RB proteins.

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