Viruses Flashcards
Discovery
Tobacco mosaic virus-sap+filter-found out
1892-Dr Ivanoski-Russian-filtering method for bacterial isolation,filtered sap could still transmit disease
1898-dr Beijerick called it a virus-polish-pass through filter with small pores,thought agent to be fluid
Characteristics
infectious agents with gentic material in protein coat-single or double strand,rna or DNA
require hosts
reproduce by replication +assembly not dividing
Shapes
Typical shapes
Polyhedral-human papillomavirus
Spherical-herpes virus
Helical-Ebola+tobacco mosiac virus
Complex shapes-infect all types,different shapes=different hosts
Structure
Nucleocapsid-nucleoic acid+protein capsid
Mature virus-Virion=extracellular virus particle outside host
non-enveloped virus
Cell lysis-allows virus to escape
Exocytosis-host cell dies
Host cell to lice +rupture
Enveloped virus
host cell doesn’t die
bud out
Exocytosis
Viral infection steps 1-4
- binding
2-entry a +b - release +nucleuar transport
- nuclear entry
viral infection steps 5-8
5.gene expression
6. Dna Replication
7.Packaging
8.Egress
attachment
Random collision
Viral protein binds host cell surface receptor
Host range-Host-specificity detirminatant
determinant for infection
Genome entry
non-enveloped-direct
Endocytosis by host
inject nucleic acid
Genome entry-enveloped
Endocytosis by host-uptake
membrane fusion-bind
entire virion
location of nucleic acid=virus
Baltimore system
Divide all viruses into seven groups based on how the viral mRNA is produced
Generation of proteins
replication
binding +entry
viral lifestyles:Lytic+ Latent
Lytic vs Latent
Lytic-makes own proteins, Active
Latent-more virus not made
Lytic replication
Active=virus making more virus
temporal cascade of gene expression
makes more of itself
progeny virions produced
Ex;Influzena virus
