Which of the following is a mechanism by which eukaryotes normally regulate gene expression?

• A. Operon repression
• B. RNA splicing
• C. DNA methylation
• D. Alternative promoter usage

Answer: (C)

Verified step by step guidance

1. Understand that gene expression regulation in eukaryotes involves multiple mechanisms that control when and how genes are transcribed, processed, and translated into proteins.
2. Recognize that 'operon repression' is a mechanism primarily found in prokaryotes, not eukaryotes. Eukaryotes do not use operons for gene regulation.
3. Learn that 'RNA splicing' is a eukaryotic mechanism where introns (non-coding regions) are removed from pre-mRNA, and exons (coding regions) are joined together. This process is essential for producing mature mRNA.
4. Understand that 'DNA methylation' is a key epigenetic mechanism in eukaryotes. It involves the addition of methyl groups to cytosine bases in DNA, typically leading to gene silencing by preventing transcription factors from binding to the DNA.
5. Recognize that 'alternative promoter usage' is another eukaryotic mechanism where different promoters are used to initiate transcription, resulting in the production of different mRNA variants from the same gene.