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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Ch. 24 - Cancer Genetics
Klug12th EditionConcepts of Genetics ISBN: 9780135564776
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Table of contents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
Chapter 24, Problem 21
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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Understand that radiotherapy controls or cures cancer primarily by causing damage to the DNA of cancer cells, leading to cell death or preventing their ability to divide and proliferate.
Recognize that ionizing radiation induces DNA double-strand breaks and other types of damage, which, if unrepaired or misrepaired, trigger apoptosis (programmed cell death) or senescence in cancer cells.
Consider that radiotherapy targets rapidly dividing cells, which is a characteristic of many cancer cells, making them more susceptible to DNA damage compared to most normal cells.
Acknowledge that significant side effects occur because radiotherapy can also damage normal, healthy cells in the surrounding tissues, especially those that also divide rapidly, such as cells in the skin, gastrointestinal tract, and bone marrow.
Note that the extent of side effects depends on factors like radiation dose, treatment area, and individual patient sensitivity, which explains why side effects can vary widely among patients.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Mechanism of DNA Damage by Ionizing Radiation
Ionizing radiation used in radiotherapy causes breaks in DNA strands, especially double-strand breaks, which can lead to cell death or malfunction. Cancer cells, which divide rapidly, are more susceptible to this damage, leading to their destruction or growth inhibition.
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04:29
Induced Mutations
Selective Targeting of Cancer Cells
Radiotherapy aims to target cancer cells more than normal cells by exploiting differences like rapid division and impaired DNA repair in tumors. However, some normal cells near the tumor are also affected, which limits the dose and effectiveness.
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09:46Cancer Characteristics
Side Effects Due to Damage of Normal Cells
Radiotherapy can harm healthy tissues surrounding the tumor, causing side effects such as inflammation, fatigue, and tissue damage. These effects arise because normal cells also experience DNA and cellular damage, especially in rapidly dividing tissues like skin and mucosa.
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03:38Maternal Effect
Related Practice
Textbook Question
Describe the difference between an acute transforming virus and a virus that does not cause tumors.
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Textbook Question
Epigenetics is a relatively new area of genetics with a focus on phenomena that affect gene expression but do not affect DNA sequence. Epigenetic effects are quasi-stable and may be passed to progeny somatic or germ-line cells. What are known causes of epigenetic effects, and how do they relate to cancer?
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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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Textbook Question
Explain the apparent paradox that both hypermethylation and hypomethylation of DNA are often found in the same cancer cell.
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Textbook Question
As part of a cancer research project, you have discovered a gene that is mutated in many metastatic tumors. After determining the DNA sequence of this gene, you compare the sequence with those of other genes in the human genome sequence database. Your gene appears to code for an amino acid sequence that resembles sequences found in some serine proteases. Conjecture how your new gene might contribute to the development of highly invasive cancers.
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