You should be familiar with viruses, but we were trying to focus on the hardest and/or more significant material that will be on the test. With viruses, there's a few things they'll want you to know.1. Viruses typically are lytic or lysogenic-a. Lytic viruses insert their DNA or RNA and make the infected cell start making 1000's of new viruses until the cell dies/bursts-b. Lysogenic viruses insert their genes into the host cell's DNA. Every time the host divides, the virus' genes gets copied as well. Ultimately the viral genes may become active and cause the cell to enter the lytic stage, killing the host as it makes more copies of the virus2. Retrovirus- a kind of virus that uses RNA instead of DNA-a. Retroviruses (and other similar viruses) are useful tools for genetic engineering-b. Retroviruses use an enzyme called Reverse Transcriptase to make DNA copies of their RNA to insert into the host's DNA.-c. Retroviruses include HIV-d. HIV targets Helper T cells of the immune sys.