Ch. 6.3- Introduction to viral replication pathways Flashcards
What are the five key steps to the lytic replication pathway that bacteriophages use?
1) Attachment- attachment to the host bacterial cell
2) Penetration- injection of genome into the host- empty capsid remains outside the cell.
3) Replication- protein synthesis makes phage parts and genome is replicated- host cell DNA is broken down by virus DNAases
4) Assembly- Genome is packed into capsids and phage structures are assembled
5) Release- Bacterial cell lyses and new phages are released.
Define DNAases
DNA degrading enzymes that are designed to break down host cell DNA.
What are the five steps in lysognic replication cycle?
1) Attachement- same as lytic replication
2) Penetration- same as lytic replication
3) Replication- phage genome is incorporated into host cell genome forming a prophage. In this step, the infected bacterial cell replicates it’s own genome as well as the phages genome.
4) Assembly- if the host cell becomes stressed, the phage my remove itself from the genome of the cell and enter the lytic replication pathway where the genome is packed into the capsid and phages structures are assembled.
5) Release- the phages “abandon ship” before the host cell dies.
What two pathways do temperate phages use to replicate themselves?
lytic and lysogenic replication cycles.
Define phage conversion
When new pathogenic properties are given to bacterial cells by bacteriophage viruses.
What are the six steps of the animal virus replication cycle?
1) Attachement- Naked viral capsid proteins attach to host cell membrane
2) Penetration- Occurs by fusion of endocytosis
3) Uncoating- Genome is released from the capsid
4) Replication- Genome is replicated and viral proteins are made
5) Assembly- New virions are assembled
6) Release- Virions are released by budding or lysis
Describe membrane fusion
When the host cell plasma membrane and the viral envelope blend together.
Where do enveloped viruses get there envelope from?
They get it from the plasma membrane of the host cell as they leave the cell.
Define acute infections
Infections caused by viruses that use the animal virus replication cycle where they enter the host cell and immediately begin forming new viruses.
Define latent persistent infection morphology
Infection will flare at some point after viral invasion occurs, then it will die down, but periodically flare up over time.
I.E.- Herpes (cold sore version), chicken pox
Define chronic persistent infection morphology
Infection will enter and not cause severe problems immediately, but gets consistently worse over time.
This is caused by continuous release of virions over time and a slow progression of the disease.
Define episomally
When a virus genome exists outside the host cells genome.
