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?
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 23c
Amino acids are classified as positively charged, negatively charged, or electrically neutral.
How does acetylation of lysine affect its interaction with DNA, and how is this related to the activation of gene expression?
Verified step by step guidance1
Understand the properties of lysine: Lysine is a positively charged amino acid due to its amine group in the side chain. This positive charge allows lysine to interact with the negatively charged phosphate backbone of DNA through electrostatic interactions.
Explain acetylation: Acetylation is a chemical modification where an acetyl group (CH₃CO) is added to the amine group of lysine. This process neutralizes the positive charge on lysine, reducing its ability to interact with negatively charged DNA.
Relate acetylation to chromatin structure: DNA is wrapped around histone proteins to form chromatin. When lysine residues in histones are acetylated, the reduced interaction between histones and DNA leads to a more relaxed chromatin structure, known as euchromatin.
Connect chromatin relaxation to gene expression: The relaxed chromatin structure allows transcription factors and RNA polymerase easier access to the DNA, facilitating the transcription of genes and thereby activating gene expression.
Summarize the relationship: Acetylation of lysine reduces its positive charge, weakens its interaction with DNA, relaxes chromatin structure, and promotes gene expression by making the DNA more accessible to the transcriptional machinery.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acetylation
Acetylation is a post-translational modification where an acetyl group is added to a molecule, often a protein. In the context of lysine, an amino acid with a positively charged side chain, acetylation neutralizes its charge. This modification can alter the protein's structure and function, impacting its interactions with other molecules, such as DNA.
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Histone Protein Modifications
Histone Modification
Histone modification refers to the chemical changes to histone proteins, which package and order DNA into structural units called nucleosomes. Acetylation of lysine residues on histones reduces their positive charge, decreasing their affinity for negatively charged DNA. This relaxation of DNA structure facilitates access for transcription factors, thereby promoting gene expression.
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Gene Expression Regulation
Gene expression regulation involves the processes that control the timing and amount of gene product (RNA or protein) produced. Acetylation of histones is a key mechanism in this regulation, as it can lead to chromatin remodeling and increased transcriptional activity. Understanding how acetylation affects gene expression is crucial for comprehending cellular responses and developmental processes.
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Related Practice
Textbook Question
Amino acids are classified as positively charged, negatively charged, or electrically neutral.
Which category includes lysine?
Textbook Question
Amino acids are classified as positively charged, negatively charged, or electrically neutral.
How does this property of lysine allow it to interact with DNA?
Textbook Question
Methylation of H3K9 by itself silences genes, but if H3K4 and H4K20 are also methylated, the combination of modifications stimulates transcription. What conclusions can you draw about this?