Textbook Question
How does an environmental factor like stress generate a response that is transmitted from generation to generation?
Ch. 19 - Epigenetics
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 19, Problem 2
Write a short essay describing how epigenetic changes in cancer cells contribute to the development and maintenance of cancers.
Verified step by step guidance1
Begin by defining epigenetics: Explain that epigenetics refers to heritable changes in gene expression that do not involve alterations to the DNA sequence itself. These changes are often mediated by mechanisms such as DNA methylation, histone modification, and non-coding RNA activity.
Describe how epigenetic changes can lead to cancer: Discuss how abnormal epigenetic modifications can silence tumor suppressor genes or activate oncogenes. For example, hypermethylation of promoter regions in tumor suppressor genes can prevent their expression, while hypomethylation in oncogene regions can lead to their overexpression.
Explain the role of histone modifications: Highlight how changes in histone acetylation or methylation can alter chromatin structure, making certain regions of DNA more or less accessible for transcription. This can disrupt normal cellular processes and contribute to uncontrolled cell growth in cancer.
Discuss the maintenance of cancer through epigenetic changes: Explain how cancer cells can use epigenetic mechanisms to adapt to their environment, resist therapies, and maintain their malignant state. For instance, epigenetic plasticity allows cancer cells to switch between different states, aiding in metastasis and survival under stress conditions.
Conclude with therapeutic implications: Briefly mention how understanding epigenetic changes in cancer has led to the development of epigenetic therapies, such as drugs targeting DNA methylation (e.g., azacitidine) or histone deacetylases (HDAC inhibitors), which aim to reverse these abnormal modifications and restore normal gene expression.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Epigenetics
Epigenetics refers to the study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence. These changes can be influenced by various factors, including environmental stimuli, lifestyle, and developmental stages. In cancer, epigenetic modifications can lead to the activation of oncogenes or the silencing of tumor suppressor genes, contributing to tumorigenesis.
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Chromatin
DNA Methylation
DNA methylation is a key epigenetic mechanism that involves the addition of a methyl group to the DNA molecule, typically at cytosine bases. This modification can repress gene expression and is often found in cancer cells, where abnormal methylation patterns can silence genes that normally prevent tumor growth. Understanding these patterns is crucial for identifying potential biomarkers and therapeutic targets in cancer treatment.
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Histone Modification
Histone modification involves the chemical alteration of histone proteins around which DNA is wrapped, influencing chromatin structure and gene accessibility. Common modifications include acetylation, methylation, and phosphorylation, which can either promote or inhibit gene expression. In cancer, abnormal histone modifications can lead to the dysregulation of genes involved in cell cycle control and apoptosis, thereby supporting cancer cell survival and proliferation.
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Related Practice
Textbook Question
How do we know how methylation of promoters silences gene expression?
Textbook Question
What is the evidence that epigenetic changes are involved in cancer?
Textbook Question
What are the major mechanisms of epigenetic genome modification?
Textbook Question
What parts of the genome are reversibly methylated? How does this affect gene expression?
Textbook Question
Identical twins each carry the same genome, but over time, can develop different phenotypes. How can you explain this?