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

Overview of Cancer

Genetics

19. Cancer Genetics

Overview of Cancer

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1:32 minutes

Problem 1c

Textbook Question

How do we know that cancer cells contain defects in DNA repair?

Verified step by step guidance

Understand that cancer is fundamentally a genetic disease, meaning it arises due to mutations or alterations in the DNA. These mutations can affect genes responsible for DNA repair, leading to defects in the repair mechanisms.

Recognize that researchers have identified specific genes, such as BRCA1 and BRCA2, which are involved in DNA repair. Mutations in these genes are strongly associated with certain types of cancer, such as breast and ovarian cancer.

Examine experimental evidence: Scientists have observed that cancer cells often accumulate a higher number of mutations compared to normal cells. This accumulation suggests that the mechanisms responsible for correcting DNA damage are impaired in cancer cells.

Consider studies using model organisms or cell lines: When researchers disable DNA repair genes in experimental systems, they observe an increased likelihood of cancer development, further supporting the link between DNA repair defects and cancer.

Review clinical observations: Patients with inherited syndromes, such as Lynch syndrome or Xeroderma Pigmentosum, which involve mutations in DNA repair genes, have a significantly higher risk of developing cancer. This provides direct evidence of the role of DNA repair defects in cancer.

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Key Concepts

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

DNA Repair Mechanisms

DNA repair mechanisms are cellular processes that identify and correct damage to the DNA molecules that encode the genome. These mechanisms are crucial for maintaining genomic stability and preventing mutations that can lead to diseases, including cancer. Defects in these repair systems can result in the accumulation of genetic errors, which is a hallmark of cancer cells.

Cell Cycle Regulation

The cell cycle is a series of phases that a cell goes through to grow and divide. Proper regulation of the cell cycle ensures that cells only divide when they are ready and that any DNA damage is repaired before division occurs. Cancer cells often exhibit dysregulation of the cell cycle, allowing them to proliferate uncontrollably despite having DNA damage.

Mutations and Cancer Development

Mutations are changes in the DNA sequence that can lead to altered protein function and contribute to cancer development. When DNA repair mechanisms fail, mutations can accumulate, leading to the activation of oncogenes or the inactivation of tumor suppressor genes. This accumulation of genetic alterations is a critical step in the multi-step process of cancer progression.

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