Textbook Question
If a cell suffers damage to its DNA while in S phase, how can this damage be repaired before the cell enters mitosis?
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Ch. 19 - The Genetics of Cancer
Klug10th EditionEssentials of GeneticsISBN: 9780135588789
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Table of contents
- Ch. 1 - Introduction to Genetics16
- Ch. 2 - Mitosis and Meiosis28
- Ch. 3 - Mendelian Genetics37
- Ch. 4 - Modification of Mendelian Ratios53
- Ch. 5 - Sex Determination and Sex Chromosomes32
- Ch. 6 - Chromosome Mutations: Variation in Number and Arrangement37
- Ch. 7 - Linkage and Chromosome Mapping in Eukaryotes36
- Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages24
- Ch. 9 - DNA Structure and Analysis38
- Ch. 10 - DNA Replication29
- Ch. 11 - Chromosome Structure and DNA Sequence Organization22
- Ch. 12 - The Genetic Code and Transcription36
- Ch. 13 - Translation and Proteins27
- Ch. 14 - Gene Mutation, DNA Repair, and Transposition34
- Ch. 15 - Regulation of Gene Expression in Bacteria22
- Ch. 16 - Regulation of Gene Expression in Eukaryotes37
- Ch. 17 - Recombinant DNA Technology27
- Ch. 18 - Genomics, Bioinformatics, and Proteomics30
- Ch. 19 - The Genetics of Cancer21
- Ch. 20 - Quantitative Genetics and Multifactorial Traits37
- Ch. 21 - Population and Evolutionary Genetics45
Chapter 19, Problem 15
How do translocations such as the Philadelphia chromosome contribute to cancer?
Verified step by step guidance1
Understand that a translocation is a chromosomal abnormality where a segment of one chromosome breaks off and attaches to another chromosome, potentially disrupting normal gene function.
Recognize that the Philadelphia chromosome is a specific translocation between chromosomes 9 and 22, denoted as t(9;22)(q34;q11), which fuses parts of two genes: BCR from chromosome 22 and ABL from chromosome 9.
Learn that this fusion creates a novel BCR-ABL gene that encodes a constitutively active tyrosine kinase enzyme, which means it is always 'on' and continuously signals cells to divide.
Understand that this uncontrolled signaling leads to increased cell proliferation and reduced apoptosis (programmed cell death), contributing to the development of cancer, specifically chronic myelogenous leukemia (CML).
Summarize that translocations like the Philadelphia chromosome contribute to cancer by creating abnormal fusion genes that produce proteins disrupting normal cell cycle regulation and promoting malignant transformation.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Chromosomal Translocations
Chromosomal translocations occur when segments from two different chromosomes break and reattach to each other. This rearrangement can disrupt normal gene function or create novel gene fusions, which may alter cellular behavior. Translocations are a common genetic abnormality in various cancers.
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12:42
Reciprocal Translocation
Philadelphia Chromosome
The Philadelphia chromosome is a specific translocation between chromosomes 9 and 22, producing the BCR-ABL fusion gene. This abnormal gene encodes a constitutively active tyrosine kinase that drives uncontrolled cell division, primarily associated with chronic myeloid leukemia (CML).
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07:10Chromosome Structure
Oncogene Activation and Cancer Development
Oncogenes are mutated or abnormally expressed genes that promote cancer. Translocations can activate oncogenes by creating fusion proteins or misregulating gene expression, leading to increased cell proliferation and survival. This process is a key mechanism by which genetic changes contribute to cancer.
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04:46Cancer Mutations
Related Practice
Textbook Question
Distinguish between oncogenes and proto-oncogenes. In what ways can proto-oncogenes be converted to oncogenes?
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Textbook Question
Of the two classes of genes associated with cancer, tumor-suppressor genes and oncogenes, mutations in which group can be considered gain-of-function mutations? In which group are the loss-of-function mutations? Explain.
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Textbook Question
How do normal cells protect themselves from accumulating mutations in genes that could lead to cancer? How do cancer cells differ from normal cells in these processes?
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Textbook Question
Radiotherapy (treatment with ionizing radiation) is one of the most effective current cancer treatments. It works by damaging DNA and other cellular components. In which ways could radiotherapy control or cure cancer, and why does radiotherapy often have significant side effects?
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Textbook Question
Genetic tests that detect mutations in the BRCA1 and BRCA2 tumor-suppressor genes are widely available. These tests reveal a number of mutations in these genes—mutations that have been linked to familial breast cancer. Assume that a young woman in a suspected breast cancer family takes the BRCA1 and BRCA2 genetic tests and receives negative results. That is, she does not test positive for the mutant alleles of BRCA1 or BRCA2. Can she consider herself free of risk for breast cancer?
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