Which of the following statements is not true for retroviruses :-
A
Retroviruses carry gene for RNA-dependent DNA polymerase
B
The genetic material in mature retroviruses is RNA
C
Retroviruses are causative agents for certain kinds of cancer in man
D
DNA is not present at any stage in the life cycle of retroviruses.
The answer is D.
Solution
Retroviruses (e.g. HIV, and oncogenic viruses such as HTLV) have RNA as their genetic material in the mature virus particle; true. They carry the gene for the enzyme reverse transcriptase (RNA-dependent DNA polymerase); true. Inside the host cell, reverse transcriptase copies the viral RNA into DNA. This viral DNA integrates into the host genome as a provirus and is then transcribed to make new viral RNA. So DNA is definitely present at one stage of the life cycle. Some retroviruses cause certain kinds of cancer in humans (e.g. HTLV-1 causes T-cell leukaemia); true. So the statement that is not true is: DNA is not present at any stage in the life cycle of retroviruses.
ConceptLife cycle of retroviruses
Human Health and Disease in past papers
121 questions from this chapter have appeared across 27 exam years.
