Bio Final Prep - Viruses

• -Nucleic acid
• -A protein coat
• -(in some) a membranous envelope

Double or single stranded DNA or RNA

• the protein shell that encloses the viral genome
• -it's built of subunits called capsomeres

the capsids of viruses

The lytic and lysogenic cycles

• Death of the host cell.
• A phage that only undergoes the lytic cycle is called a virulent phage

• Attachment
• Entry of phage DNA, degredation of host DNA
• Synthesis of viral genomes and proteins
• Assembly
• Release

does not destroy the cell

when viral DNA is incorporated into the host's chromosome during the lysogenic cycle

• Phage injects the DNA into the cell
• Prophage
• The bacterium reproduces, copying the prophage
• Cell divison produces more - daughter cells with prophase

Phages that use both the lytic and lysogenic cycles

• 1) DNA or RNA?
• 2) Single or double stranded

• Plasmids - circular DNA in bacteria and yests
• Transposons - small mobile DNA segments

plants, and disrupt their growth

• cause brain diseases in mammals
• *Prions propagate by converting normal proteins to prions