chapter 5: viruses and prions Flashcards
what is a virus?
infectious agent w acellular organization having a protein coat (capsid) and nucleic acid genome
TRUE or FALSE: Pasteur hypothesized that rabies was caused by a virus and developed a vaccine
TRUE
why are viruses known as “filterable”?
they become attached to molecules of host organisms
bacteriophage are what…
a virus that infects a bacterial cells
what does a virus consist of?
capsid and DNA/RNA
envelope
lipid layer outside (external to) nucleocapsid
-think covering
envelope proteins are coded for by virus
MES (membrane, envelope and spike)
what are spikes?
proteins on outer surfaces that project from envelope
functions of capsid?
-surrounds viral genome
-protects genomes
-aids in host invasion
types of capsid symmetry?
helical capsid: think dna shape
Icosahedral capsid: 20 faces
complex capsid: diamond shape
TRUE OR FALSE: genome can be circular or linear?
TRUE
phases of the animal viral replication cycle:
-adsorption: virus attach via spikes to receptors on host cell
-penetration: virus enter host
-synthesis: viruses enters cell’s nucleus (think replication and protein production)
-assembly: complete virus construction from various viral parts
-release: by host cell lysis
2 types of viral infections?
eukaryotic cell viral infections and bacterial cell viral infections
TRUE or FALSE: some viral infections do not kill host but stay in cell as persistent/chronic infection
TRUE
(think dormanent)
phages can either be…
virulent or temperate
describe the types of phages?
-VIRULENT: multiplies immediately upon entry
-TEMPERATE: the silent virus! (think dominant)
lysogenic conversion?
temperate phage change phenotype of host cell
TRUE OR FALSE: viruses are unable to reproduce outside of living host cells
TRUE
what are prions?
infectious particles composed of proteins
what are non-cellular infectious agents?
viruses, prions, satellites, and viroids
