Questions and Answers
What is p53 often referred to as?
What is the main function of p21?
What happens when tumor suppressor genes have a defect or loss of function?
What percentage of tumors have a defect in p53?
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What is the role of RB protein in the cell cycle?
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What is the relationship between p53 and RB?
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What is the impact of a defect in tumor suppressor genes?
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What is the significance of p53 being called 'the molecule of the year'?
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What is the main reason why RB is considered a tumor suppressor gene?
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What is unique about P21 compared to other tumor suppressor genes?
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What happens to mice that lack P21?
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Why is it important to regulate the cell cycle?
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What is required for mitosis, or cell division, to happen?
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Why do tumor suppressor genes regulate cell division?
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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.