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Multiple Choice
What occurs during histone acetylation and how does it affect gene expression?
A
Histone acetylation adds acetyl groups to histones, leading to increased gene expression by loosening chromatin structure.
B
Histone acetylation adds methyl groups to histones, leading to increased gene expression by loosening chromatin structure.
C
Histone acetylation removes acetyl groups from histones, leading to decreased gene expression by tightening chromatin structure.
D
Histone acetylation removes methyl groups from histones, leading to decreased gene expression by tightening chromatin structure.
Verified step by step guidance
1
Understand the role of histones: Histones are proteins that help package DNA into a compact, structured form called chromatin. This packaging can influence gene expression by controlling the accessibility of DNA to transcription machinery.
Define histone acetylation: Histone acetylation is a chemical modification where an acetyl group (CH₃CO) is added to the lysine residues on histone proteins. This process is catalyzed by enzymes known as histone acetyltransferases (HATs).
Explore the effect of acetylation on chromatin structure: The addition of acetyl groups neutralizes the positive charge on histones, reducing their affinity for the negatively charged DNA. This results in a more relaxed chromatin structure, known as euchromatin.
Connect chromatin structure to gene expression: When chromatin is in a relaxed state, transcription factors and RNA polymerase can more easily access the DNA, leading to increased transcription and gene expression.
Clarify the misconception: Histone acetylation does not involve the addition or removal of methyl groups. Methylation is a separate modification that can have different effects on gene expression.