Final answer:
The correct order is RNA, reverse transcription, DNA, provirus, with reverse transcriptase and ligase enzymes involved.
Step-by-step explanation:
The correct order of events is as follows:
RNA
Reverse transcription
DNA
Provirus
RNA is the first step, followed by reverse transcription which uses the viral RNA as a template to synthesize DNA. This DNA then forms a provirus, which integrates into the DNA of the host cell. The enzymes involved in these transitions are reverse transcriptase and ligase.
The sequence for a retrovirus such as HIV entering a host cell is RNA, reverse transcription to DNA, formation of a provirus, transcription to mRNA, and synthesis of proteins. The enzyme reverse transcriptase is key to converting RNA into cDNA, and ligase integrates the DNA into the host genome. This process is an exception to the central dogma which is normally DNA to RNA to protein.
The correct sequence of events when a retrovirus infects a host cell is as follows:
RNA: The retrovirus, such as HIV, enters the host cell with its RNA genome.
Reverse transcription: The enzyme reverse transcriptase converts the viral RNA into a complementary DNA (cDNA) strand.
DNA: The cDNA strand is then converted into a double-stranded DNA molecule.
Provirus: This DNA is integrated into the host cell's genome using the enzyme ligase. At this point, it is considered a provirus.
mRNA is then transcribed from the integrated DNA.
Protein synthesis: The host's cellular machinery translates the viral mRNA into viral proteins and enzymes necessary for assembling new virions.
This process differs from the central dogma of molecular biology which typically follows the path of DNA to RNA to protein. Retroviruses invert a part of this sequence using reverse transcription to go from RNA to DNA.