Question

Which one of the following molecules can be used for RNA interference?

• A. double-stranded RNA molecule containing Uracil
• B. single-stranded RNA molecule (contains U)
• C. single-stranded DNA molecule (contains T instead of U)
• D. double-stranded DNA molecule (contains T and complementary base pairing)

Hint:

RNA interference (RNAi) always requires double-stranded RNA (dsRNA).
Look for two complementary strands and check for the letter "U" (Uracil), which distinguishes RNA from DNA (which has "T").

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks us to identify which of the molecular structures shown can be used to initiate RNA interference (RNAi) inside a eukaryotic cell.

Step 2: Key Formula or Approach:
RNA interference is a biologically conserved process where double-stranded RNA (dsRNA) molecules are used to silence specific gene expression.
To be effective, the silencing agent must be:
1. Double-stranded to be recognized by the Dicer enzyme.
2. Composed of RNA nucleotides (which contain Uracil 'U' instead of Thymine 'T').

Step 3: Detailed Explanation:
Let's analyze the options:

• Option (A):
- This is a double-stranded molecule as shown by the complementary base-pairing lines ($|$).
- It contains Uracil (U) and no Thymine (T). This confirms it is a double-stranded RNA (dsRNA) molecule.
- Dicer can recognize and cleave this dsRNA into small interfering RNAs (siRNAs) to initiate target mRNA cleavage. Thus, this can be used for RNAi.

• Option (B):
- This is a single-stranded RNA molecule (contains U). Single-stranded RNA does not trigger the RNAi pathway directly without being converted or folded.

• Option (C):
- This is a single-stranded DNA molecule (contains T instead of U). DNA cannot be used for direct RNA interference.

• Option (D):
- This is a double-stranded DNA molecule (contains T and complementary base pairing). dsDNA is the standard genetic material and does not trigger RNAi.

Step 4: Final Answer:
Option (A) represents a complementary double-stranded RNA molecule, which is the required substrate for initiating RNA interference.