Final answer:
The conversion of retroviral RNA into linear DNA is facilitated by the enzyme reverse transcriptase. This process occurs as the first step after a retrovirus, like HIV, infects a host cell and releases its RNA, leading to integration into the host DNA.
Step-by-step explanation:
Conversion of retroviral RNA template into the linear DNA occurs in the presence of the enzyme reverse transcriptase. Retroviruses, such as HIV, carry their genetic information in single-stranded RNA (ssRNA) and, upon infection of a host cell, use reverse transcriptase to synthesize complementary DNA (cDNA) from the RNA template. This reverse transcription process is the opposite of normal transcription, which involves the synthesis of RNA from a DNA template, hence why it is termed 'reverse.' The newly formed cDNA is then converted into double-stranded DNA (dsDNA), which can integrate into the host's genome as a provirus, becoming a permanent fixture and enabling chronic infection.
Once integrated, the provirus DNA can direct the synthesis of new viral RNA and proteins, leading to the formation of new virions that can exit the host cell and infect others. In the case of HIV, reverse transcription takes place in the cytoplasm of the T-lymphocyte, followed by integration into the host genome, utilizing the host's cellular machinery to replicate the virus and produce viral particles.