Question

Which one is the structure of Uracil in RNA?

• A. It is a purine base with a double ring
• B. It is similar to thymine (5-methyl uracil), but lacks the methyl group
• C. It only binds with deoxyribose sugar
• D. It forms hydrogen bonds with guanine

Hint:

\[ \boxed{\text{Uracil (RNA) ↔ Adenine pairing}} \] \[ \boxed{\text{Thymine (DNA) = Uracil + CH}_3} \]

Answer 1

The Correct Option is B

Concept: Uracil is a pyrimidine base found in RNA. It replaces thymine in DNA.

Step 1: Understand structure.
Uracil is a single-ring pyrimidine base and is structurally similar to thymine. \[ \boxed{\text{Uracil = Thymine without CH}_3 \text{ group}} \]

Step 2: Check pairing rules.
Uracil pairs with adenine in RNA through hydrogen bonding.

Step 3: Evaluate options.

• (A) Incorrect → purine is double ring.

• (B) Correct → uracil is like thymine without methyl group.

• (C) Incorrect → RNA uses ribose sugar, not deoxyribose.

• (D) Incorrect → uracil pairs with adenine, not guanine.
Thus, \[ \boxed{\textbf{Option (B)}} \]