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Questions and Answers
What is the role of KRAS in normal cell growth?
What is the result of the chromosome translocation between the long arms of chromosomes 9 and 22?
What is the effect of activating the Ras oncogene?
What is the role of the tumor-suppressor gene p53?
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What is the result of losing the tumor-suppressor gene APC?
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What is the characteristic of CML cells?
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What is the effect of ultraviolet radiation on cells?
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What is the Philadelphia chromosome?
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What is the main function of oncogenes in a normal cell?
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What is the effect of activating an oncogene?
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What is the role of tumor suppressor genes?
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What is the result of inactivating a tumor suppressor gene?
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What is the name of the catalogue that provides information on somatic mutations found in cancer genes in human tumors?
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How many somatic 'cancer genes' have been identified to date?
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What is the name of the gene that acts as a switch within signal transduction pathways, including the regulation of cell division?
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What is the result of losing/damaging DNA repair genes?
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What is the outcome when a receptor protein receives a signal for cell division?
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What is a result of certain mutations in the ras sequence?
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What is the normal function of tumor suppressor genes?
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What type of mutations are commonly found in tumor suppressor genes?
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What is the role of the BRCA1 gene?
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What is a characteristic of immortalized cancer cells?
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What is required for tumor growth and survival?
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What is the process by which cancer cells travel to other parts of the body?
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Study Notes
Cell Signaling and Cancer
- Receptor proteins receive signals for cell division, activating ras, which leads to gene activation and cell division.
- Mutations in ras cause permanent activation, leading to constitutive activation of the cell cycle.
Tumor Suppressor Genes
- Over 30 genes are classified as tumor suppressors, involved in DNA repair, apoptosis, and preventing abnormal cell division.
- Loss-of-function mutations in tumor suppressor genes contribute to cancer progression.
- Examples include BRCA1, which is involved in DNA repair, and inherited mutations increase the risk of breast cancer.
Characteristics of Cancer Cells
- Cancer cells are resistant to apoptosis and have uncontrolled ability to divide.
- They are insensitive to antigrowth factors and can invade neighboring tissues.
- They can form new tumors (metastases) at distant sites and secrete chemical signals for angiogenesis.
Tumorigenesis
- Genetic changes in tumorigenesis involve gain of function (oncogenes) and loss of function (tumor suppressor genes).
- Non-lethal genetic damage is central to carcinogenesis.
Cancer Genes
- There are two types of cancer genes: tumor suppressor genes and oncogenes.
- Approximately 400 somatic "cancer genes" have been identified, with many more to be discovered.
Oncogenes
- Oncogenes are genes that promote cell growth and division in a controlled manner.
- Examples include ras, which acts as a switch in signal transduction pathways, regulating cell division.
External Causes of Cancer
- Ultraviolet radiation and tobacco smoke and diet are external causes of cancer.
Chronic Myelogenous Leukemia (CML)
- CML is a cancer of white blood cells, characterized by a consistent chromosome translocation (t(9:22)(q34;q11)) known as the Philadelphia chromosome (Ph+).
- This mutation leads to unregulated expression of a gene and its kinase product, causing activation of intracellular signaling pathways and uncontrolled proliferation of CML cells.
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Description
Learn about the role of receptor proteins, ras, and tumor suppressor genes in cell division and their impact on cancer development.