November 20th Notes

Virion: Single virus particle.

IV.) Viral Replication:
a.) Attachment- Interaction between viral proteins (usual glycoproteins) and receptors on host cell.
Absorption- Cell pulls in virion attached to its surface.
b.) Penetration/Decoating-Vacuole containing virion fuses with lysosome. Lysosome has enzymes, low pH to break down proteins. -> This breaks capsid up, freeing viral nucleic acid.
c.) Replication of nucleic acids- Virions have nucliec acids and a few enzymes needed to start the host's replication of their nucleic acids packaged in the viral capsids. -> These enzymes are also now free to help viral genome get replicated.
-DNA viruses: Enzymes (viral) help get viral DNA into nucleus (eukaryotic viruses) and patch viral DNA into host chromosome (both eukaryotic viruses and bateriophages.)
-RNA viruses: have own enzymes that start copying RNA genome -> More RNA -> Use host tRNA, rRNA, amino acids to translate RNA genomes into proteins.
-Retroviruses: RNA genome that is copied by viral enzyme reverse transcriptase into dsDNA copy - that DNA version of viral genome then patched into host cell chromosome.
d.) Synthesis of Viral proteins: DNA viruses: Proteins transcribed and translated off of viral genes in viral DNA that's now in host chromosome and DNA copies of DNA genome made.
-RNA viruses: RNA genome copied, RNA transcript translated by host ribosomes, tRNA, amino acids.
-Retro Viruses: DNA version of viral RNA genome patched into host chromosome transcribed and translated; RNA copies of viral genome transcribed to be packaged into new virions.


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