How do microRNAs regulate gene expression?

How do microRNAs regulate gene expression?

• A. By enhancing translation of target mRNAs
• B. By binding to complementary mRNAs to inhibit transcription
• C. By editing DNA sequences of target genes
• D. By binding to complementary mRNAs to inhibit translation or promote degradation

Answer: (D)

MicroRNAs regulate gene expression by guiding a silencing complex to target mRNAs based on sequence complementarity, primarily in the cytoplasm. When a microRNA binds its target, it usually represses protein production and can also cause the mRNA to be degraded. This combination—binding to complementary mRNAs to inhibit translation or promote degradation—captures the main ways miRNAs reduce gene expression. The other ideas don’t fit: enhancing translation isn’t how miRNAs work, since they generally repress expression; inhibiting transcription would involve changes at the DNA level rather than RNA, which isn’t the typical miRNA function; and editing DNA sequences is a genome-editing concept, not an RNA-level regulatory mechanism.

MicroRNAs regulate gene expression by guiding a silencing complex to target mRNAs based on sequence complementarity, primarily in the cytoplasm. When a microRNA binds its target, it usually represses protein production and can also cause the mRNA to be degraded. This combination—binding to complementary mRNAs to inhibit translation or promote degradation—captures the main ways miRNAs reduce gene expression. The other ideas don’t fit: enhancing translation isn’t how miRNAs work, since they generally repress expression; inhibiting transcription would involve changes at the DNA level rather than RNA, which isn’t the typical miRNA function; and editing DNA sequences is a genome-editing concept, not an RNA-level regulatory mechanism.