MICROM 301 Lecture Notes - Lecture 1: Rna-Dependent Rna Polymerase, Lytic Cycle, Shiga Toxin
MICROM 301 – VIRUS LECTURE
Why does a virus need a host cell?
Needs it to replicate
Can't replicate on its own
Host cell exploited to replicate virus
Envelope:
Lipid bilayer that comes from the host cell membrane
The progeny that comes out also have the envelope
Enveloped viruses are more susceptible to drying and chemicals such as disinfectants
oEnveloped = a little wimpier
Spikes are in the lipid envelope
Damaged envelope = no longer infectious
oNon enveloped = also has spikes but comes out farther
More resistant
Productive infection:
More viral particles produced
Latent state:
Virus is silent
Virus attaches to genome
Later becomes active --> productive infection
Why go to latent state?
Bacteriophage Infections:
Only affect bacteria
Attachment:
oVirus attaches to host cell via very specific receptors
oLack of receptors = resistance
Genome entry:
oInject genome (DNA) into bacterial cell
Synthesis:
oNucleic acid
oViral proteins
oHost cell DNA degraded
oAll machinery directed toward viral replication
Assembly:
oAll the parts of the virus come together to make new viral particles
Release:
oHost cell lyses which releases the virus
Number of viral particles released --> burst size (150 viral particles)
Types of Bacteriophages:
Lytic phages - lyse the cell (t4)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lipid bilayer that comes from the host cell membrane. The progeny that comes out also have the envelope. Enveloped viruses are more susceptible to drying and chemicals such as disinfectants o. Damaged envelope = no longer infectious: non enveloped = also has spikes but comes out farther. Attachment: virus attaches to host cell via very specific receptors o. Synthesis: nucleic acid, viral proteins, host cell dna degraded, all machinery directed toward viral replication. Assembly: all the parts of the virus come together to make new viral particles. Release: host cell lyses which releases the virus. Number of viral particles released --> burst size (150 viral particles) Prophage: dna of the phage carried by a lysogen o. Can be released from the genome and goes through lytic cycle. As the lawn is growing / cells multipy, the phage infects them --> infect neighboring cells --> 200 phages come out of those --> infect neighboring cells --> etc.
