Given below is a list of regulatory RNAs (Column X) and their modes of action (Column Y):

Which one of the following options represents all correct matches between Column X and Column Y?

Correct option is A

Explanation:

• Riboswitches (A) regulate gene expression by changing their conformation when bound to small molecules, usually metabolites (Statement ii).

• MicroRNA (miRNA) (B) base-pair with specific mRNAs and control their stability and translation, thus regulating gene expression at the post-transcriptional level (Statement i).

• Small interfering RNAs (siRNAs) (C) guide RISC (RNA-induced silencing complex) to mRNA targets through complementary base pairing, followed by mRNA cleavage (Statement iii).

Information Booster:

1. Riboswitches are RNA sequences that act as sensors for small molecules, and their binding causes a conformational change that regulates gene expression, often in response to metabolites.

2. miRNAs are a class of small RNA molecules that regulate gene expression by binding to target mRNA sequences, causing translational repression or degradation of the mRNA.

3. siRNAs are involved in RNA interference (RNAi), where they guide the RISC complex to complementary mRNA sequences, leading to their degradation and silencing of the gene.