GATE 2022 BT – Question 18
The type of nucleic acid present in λ−phage is
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Correct answer: (A) Double stranded DNA
Explanation
The **λ (lambda) phage** is a temperate bacteriophage of *E. coli*.
- Its genome is **double-stranded DNA** about 48.5 kb long.
- In the virion it is **linear**, with 12-base single-stranded "cos" ends that are complementary.
- After infection, the cos ends anneal and DNA ligase seals them, so the genome **circularises** in the host.
The type of nucleic acid is therefore **double-stranded DNA** (A).