Help me...

[Zebra]

What is retrovirus?

[dooodyo]

Since viruses only contain DNA or RNA a retrovirus (otherwise known as RNA virus) is simply a virus that only contains RNA strands inside its caspid (outer protein) layer.

EDIT: Had no clue that you could change colour of text 

[Russ]

That's not entirely true, retroviruses are only RNA but their defining feature is that they convert their RNA genome to DNA and integrate it back into the host cell genome (thus breaking the Crick Central Dogma).

[dooodyo]

Oh really wow thats so awesome so thats how they take over their host
Thanks for that Russ  

And what did you mean by the Crick Central Dogma?

[Russ]

Crick Central Dogma says that a cell can only ever go in one direction: DNA -> RNA -> Protein

Retroviruses break this because they go both directions: RNA -> DNA -> RNA -> Protein
They can only do it because they encode an enzyme called Reverse Transcriptase (RT) that allows DNA -> RNA transcription

Have you done RNA yet? Because there's some extra information about +ssRNA and -ssRNA that's kinda relevant but not necessary if you want it lol