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Multiple Choice
Which of the following is a method eukaryotic cells use to keep their genes turned off?
A
RNA splicing to produce multiple mRNAs
B
Enhancer binding by activator proteins
C
DNA methylation of promoter regions
D
Increased histone acetylation
Verified step by step guidance
1
Understand the context: Eukaryotic cells regulate gene expression at multiple levels, including transcriptional, post-transcriptional, translational, and post-translational stages. The question focuses on transcriptional regulation, specifically how genes are kept turned off.
Review the options: Analyze each method provided in the question to determine whether it is associated with gene silencing or activation. For example, RNA splicing and enhancer binding are mechanisms that typically enhance gene expression, not silence it.
Focus on DNA methylation: DNA methylation involves the addition of a methyl group (CH₃) to cytosine bases in DNA, often in promoter regions. This modification can block transcription factors from binding to the DNA, effectively silencing the gene.
Contrast with histone acetylation: Increased histone acetylation is associated with gene activation, as it loosens the chromatin structure, making DNA more accessible to transcription machinery. This is the opposite of gene silencing.
Conclude: DNA methylation of promoter regions is the correct method for keeping genes turned off, as it directly prevents transcription by modifying the DNA structure and accessibility.