Apentix/AP Biology/Unit 6: Gene Expression and Regulation/Question
AP Biologymediummcq1 pt

How do microRNAs lower the amount of protein produced from a particular messenger RNA in animal cells?

A.They bind promoter DNA and prevent RNA polymerase from opening the gene
B.They base-pair with complementary sequence in the target mRNA, blocking translation or triggering its decay
C.They splice introns out of the target transcript before nuclear export
D.They recode anticodons on tRNAs so ribosomes misread every codon globally

Explanation

Core Concept

Processed miRNAs load into Argonaute complexes and scan transcripts for matching sequence. Partial pairing recruits deadenylation and decay factors or simply impedes ribosome progress. Protein output drops without any change to the rate at which the gene was first transcribed.

Correct Answer

BThey base-pair with complementary sequence in the target mRNA, blocking translation or triggering its decay

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