Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

19. Cancer Genetics

Cancer Mutations

Genetics

19. Cancer Genetics

Cancer Mutations

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1:07 minutes

Problem C.8b

Textbook Question

The inheritance of certain mutations of BRCA1 can make it much more likely that a woman will develop breast or ovarian cancer in her lifetime. In addition to inheriting a BRCA1 mutation, what else must happen for a woman to develop breast or ovarian cancer?

Verified step by step guidance

Understand that BRCA1 is a tumor suppressor gene, which means it helps regulate cell growth and prevent cancer by repairing DNA damage.

Recognize that inheriting a mutation in one copy of the BRCA1 gene (germline mutation) increases cancer risk but is not sufficient alone to cause cancer.

Learn about the 'two-hit hypothesis' which states that both copies of a tumor suppressor gene must be inactivated for cancer to develop.

Identify that the second 'hit' usually involves a somatic mutation or loss of the normal BRCA1 allele in the cells of breast or ovarian tissue.

Conclude that in addition to inheriting a BRCA1 mutation, a woman must acquire a second mutation or loss of function in the other BRCA1 allele in relevant cells for cancer to develop.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

BRCA1 Gene and Its Role in Cancer

BRCA1 is a tumor suppressor gene involved in DNA repair. Mutations in BRCA1 impair this repair function, increasing the risk of breast and ovarian cancer. However, carrying a mutation alone does not guarantee cancer development; it raises susceptibility.

Multistep Nature of Cancer Development

Cancer arises through multiple genetic and environmental changes over time. Besides inheriting a mutation like BRCA1, additional mutations or cellular changes must accumulate to trigger uncontrolled cell growth and tumor formation.

Role of Environmental and Lifestyle Factors

Environmental exposures, lifestyle choices, and hormonal factors can influence cancer risk by causing DNA damage or affecting gene expression. These factors interact with inherited mutations to increase the likelihood of cancer development.

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Radiation is frequently used as part of the treatment of cancer. The radiation works by damaging DNA and components of the cell. Is there a risk of damage to noncancer cells?

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Textbook Question

Why do most cancers require the mutation of multiple genes?

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Textbook Question

Based on what you read in this chapter, Can a tumor arise from a single mutated cell? Are all the cells in a tumor identical?

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Textbook Question

The inheritance of certain mutations of BRCA1 can make it much more likely that a woman will develop breast or ovarian cancer in her lifetime. Can you say with certainty that a woman inheriting a mutation of BRCA1 will definitely develop breast or ovarian cancer in her lifetime? Why or why not?

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Textbook Question

Go to the website http://www.cancer.gov and select 'Cancer Types' on the top menu bar. Scroll down to 'Breast Cancer' and click. Select 'Cases & Prevention' from the options. Click 'More information' and select 'BRCA Mutations: Cancer Risk and Genetic Testing'. Use the information on this page to answer the following questions. Are there measures a woman with a positive result can take to lessen her chances of developing cancer or to catch a cancer early in its development?

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Textbook Question

Define tumor-suppressor genes. Why is a mutated single copy of a tumor-suppressor gene expected to behave as a recessive gene?

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Textbook Question

Go to the website http://www.cancer.gov and select 'Cancer Types' on the top menu bar. Scroll down to 'Breast Cancer' and click. Select 'Cases & Prevention' from the options. Click 'More information' and select 'BRCA Mutations: Cancer Risk and Genetic Testing'. Use the information on this page to answer the following questions. With regard to the results of genetic testing for BRCA1 and BRCA2 mutations, what is meant by a 'positive result'?

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Textbook Question

Go to the website http://www.cancer.gov and select 'Cancer Types' on the top menu bar. Scroll down to 'Breast Cancer' and click. Select 'Cases & Prevention' from the options. Click 'More information' and select 'BRCA Mutations: Cancer Risk and Genetic Testing'. Use the information on this page to answer the following questions. What are the approximate percentage increases in risk of having breast cancer and of having ovarian cancer for women inheriting harmful mutations of BRCA1 and BRCA2 compared with the risks in the general population?

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