III. a) Why viruses are specific to particular host cells is because only some kinds of cells have the "correct" surface proteins for viral proteins to attatch
c) Replication of nucleic acids
-viral nucleic acids copied by host cell enzymes, ect.
i) DNA viruses
ex. smallpox
*have DNA genomes
*host cell DNA polymerase copies viral DNA
ii) RNA viruses
ex. flu
*have RNA genome
*no living thing has an enzyme that copies RNA to RNA
*RNA replicase= RNA virus specific enzyme that copies RNA to RNA
*first step in copying RNA: translation of RNA replicase gene by host cell ribosomes and RNA
iii) Retroviruses
ex. HIV
*also have RNA genomes
RNA genome-> DNA copy (becomes part of host cell DNA)--> RNA
*reverse transcriptase= enzyme specific to retroviruses, copies RNA to RNA
d) synthesis of viral proteins
-virus uses host RNA polymerase, ribosomes, tRNA and amino acids to make its capsomeres, glycoproteins, and other viral-specific proteins
e) Assembly of new virions
-once you have all the bits, new virions spontaneously self-assemble
f) Release of new virions from host cell
i) lysis of host cell: host cell blows up, releasing new virions into the environment
ii) budding from host cell: enveloped viruses use glycoproteins to wrap selves in host cell membrane and tear free
Danya Hangman
