Textbook Question
Trace the relationship between the methylation status of the glucocorticoid receptor gene and the behavioral response to stress.
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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 22a
From the following table, draw up a list of histone H3 modifications associated with gene activation. Then draw up a list of H3 modifications associated with repression.
Are there any overlaps on the lists?
Verified step by step guidance1
Understand that histone H3 modifications are chemical changes to the histone protein that affect chromatin structure and gene expression. These modifications can either activate or repress gene transcription.
List common histone H3 modifications associated with gene activation, such as methylation at lysine 4 (H3K4me), acetylation at lysine 9 (H3K9ac), and acetylation at lysine 27 (H3K27ac). These modifications generally open chromatin and promote transcription.
List common histone H3 modifications associated with gene repression, such as methylation at lysine 9 (H3K9me) and methylation at lysine 27 (H3K27me). These modifications typically condense chromatin and inhibit transcription.
Compare the two lists to identify any overlaps. Note that some lysine residues can be modified in different ways (e.g., acetylation vs. methylation) with opposite effects on gene expression.
Summarize that while the same lysine residues on histone H3 can be targets for both activating and repressing modifications, the type of modification (acetylation vs. methylation) and the specific methylation state (mono-, di-, or tri-methylation) determine whether the effect is activation or repression.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Histone Modifications and Chromatin Structure
Histone modifications are chemical changes to histone proteins, such as methylation or acetylation, that influence chromatin structure and gene expression. These modifications can either loosen or tighten DNA packaging, thereby regulating access of transcription machinery to genes.
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Histone Protein Modifications
Histone H3 Modifications Associated with Gene Activation
Certain modifications on histone H3, like acetylation at lysine 9 (H3K9ac) and lysine 27 (H3K27ac), and methylation at lysine 4 (H3K4me3), are linked to active transcription. These marks promote an open chromatin state, facilitating gene expression.
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Histone H3 Modifications Associated with Gene Repression
Repressive histone H3 modifications include methylation at lysine 9 (H3K9me3) and lysine 27 (H3K27me3), which promote chromatin compaction and gene silencing. These marks recruit proteins that maintain a closed chromatin state, preventing transcription.
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Related Practice
Textbook Question
Prader–Willi syndrome (PWS) is a genetic disorder with a clinical profile of obesity, intellectual disability, and short stature. It can be caused in several ways. Most common is a deletion on the paternal copy of chromosome 15, but it can also be caused by an epigenetic imprinting disorder and uniparental disomy, an event in which the affected child receives two copies of the maternal chromosome 15. A child with PWS comes to your clinic for a diagnosis of the molecular basis for this condition. The gel below shows the results of testing with short tandem repeats (STRs) from the region of chromosome 15 associated with the disorder.
Is this case caused by a deletion in the paternal copy of chromosome 15? Explain.
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Textbook Question
Prader–Willi syndrome (PWS) is a genetic disorder with a clinical profile of obesity, intellectual disability, and short stature. It can be caused in several ways. Most common is a deletion on the paternal copy of chromosome 15, but it can also be caused by an epigenetic imprinting disorder and uniparental disomy, an event in which the affected child receives two copies of the maternal chromosome 15. A child with PWS comes to your clinic for a diagnosis of the molecular basis for this condition. The gel below shows the results of testing with short tandem repeats (STRs) from the region of chromosome 15 associated with the disorder.
Based on your interpretation of the data, what is the cause of PWS in this case? Explain your reasoning.
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Textbook Question
From the following table, draw up a list of histone H3 modifications associated with gene activation. Then draw up a list of H3 modifications associated with repression.
Are these overlaps explained by different modifications?
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Textbook Question
From the following table, draw up a list of histone H3 modifications associated with gene activation. Then draw up a list of H3 modifications associated with repression.
If not, how can you reconcile these differences?
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Textbook Question
Amino acids are classified as positively charged, negatively charged, or electrically neutral.
Which category includes lysine?
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