Question

Compare and contrast provirus and retrovirus.

Answer 1

as far as i know, provirus are small fragments of viral DNA that behave in a similar way as trasposons do, that is, they move along the DNA of a host cell. Retrovirus have a particular kind of RNA-polimerasa, known as retrotranscriptase. this uses the RNA of the virus as a template for DNA synthesis, so now it can become part of the genome of the host cell and express its own genes.

Answer 2

Phascolarctos is correct in that proviruses are DNA elements found in the host genome. They are a double stranded DNA copy of the RNA genome from a retrovirus and as correctly stated, reverse transcriptase is the activity that converts the RNA genome into the DNA provirus, which is then integrated into the host genome. The retrovirus is composed of protein and DNA - the proteins come from the provirus and make up the protein coat of the retrovirus, along with the reverse transcriptase which is necessary for the life cycle. The three genes on a simple retrovirus are called gag, pol and env by the way. I hope this makes things clearer.