Viruses Flashcards
What are virons
Virus particles, biologically inert don’t divide
What do non-enveloped viruses contain
Capsid
Capsomere
Nucleic acid
What is the function of a capsid
Encapsulates nucleic acids - no harm
Interacts with cell organelles
Genome delivery - binds to receptor using spikes
What shapes could a capsomere be
Rod
Spheres
What does the capsid protect the genome against
Physical damage
Chemical damage
Enzymatic damage
What is a spherical capsid like
Formed by repeating protein units
Some have spikes (will only bind to certain receptors on host cell)
What is a helical rod-like capsid like
Proteins wrap round nucleic acid
Protein helix length determined by nucleic acid length
What does an enveloped virus consist of
Lipid bilayer
Capsomere
Envelope
Nucleic acid
What makes up a nucleocapsid
Capsomere and nucleic acid
What is the lipid bilayer function for enveloped virus
Allows fusion to host cell wall
How does enveloped virus enter/exit host without total destruction
Envelope pinches off bit of plasma membrane, envelope glycoprotein on outside of capsomere fuses with outside of cell, release nuclear capsid into cytosol
What are the stages of phage
Virus adsorbed onto host Penetrate by injecting DNA into host Nucleic acid replication DNA replicates, will encode for protein coat to encapsulate virus Nucleic acid 'stuffed' into virus Virus released
Lytic infection
Host cells destroyed - virus particles released
Normally clears in couple days - immunity
Some hosts not immune, can cause epidemics
Persistant / chronic infection
Virus doesn’t cause cell death, slow virus release without death
If not good immunity - can last a long time
Latent infection
Lack of gene expression, normally in sensory and autonomic ganglia - immunocompromised
Lasts lifetime of host
UV can cause reactivation - re-enter lytic cycle
