Question

What is not true for retrovirus ?

• A. DNA has no role in the life cycle
• B. There is a gene for RNA dependent DNA polymerase
• C. Genetic material is RNA
• D. They are causative agents for certain cancers.

Answer 1

Answer: (A)

DNA has no role in the life cycle

Retroviruses are single-stranded RNA virus belongs to the family retroviridae. Retrovirus carry the genes for reverse transcriptase enzyme which is a RNA dependent DNA polymerase. This enzyme uses RNA as a primer to synthesise cDNA which is then incorporated into the host genome. The host cell then treats the viral DNA as part of its own genome, transcribes and translates the viral genes along with the cell's own genes producing the proteins required to assemble new copies of the virus. This explains the important role of DNA in life cycle. Retroviruses cause tumour growth and certain cancers in animals. So the correct answer is 'DNA has no role in life cycle'.