BIL 150 Lecture Notes - Lecture 18: Viral Envelope, Capsid, Fetus
7 Nov 2016
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Document Summary
Do not have all 8 living characteristic features. Virus can live outside a host cell for small time or for years. Requires a living cell to survive and multiple. Mutate very fast so they evolve very fast. Very difficult to develop vaccines because of this. Size : 17 nm - 3000 nm diameter. Hijack host cell dna and utilize for own replication and survival. Viral dna is released; uses host cell dna polymerase to multiple. Enters the cell, attaches to the host cell membrane. Mrna goes into the cell (outer capsomeres disintegrate) Lytic cycle: the lytic cycle is a phage replicative cycle that ends in the death of the host cell. Produces new phages and lyses (breaks open) the host cell, releasing the progeny viruses. Phage that reproduces only by the lytic cycle is called a virulent phage. Bacteria have defenses against phages, including restriction enzymes that recognize and cut up certain phage dna.
