Bacteriohages

Question 1

Bacteriophage structure?

Answer 1

Genomic Ds linear DNA

Has a capsid a tail and adsorption apparatus

Question 2

How does bacteriophage adsorption work?

Answer 2

First there is reversible binding and the bacteriophage moves around to bind irreversibly. Then you have DNA injection into the cell.

Question 3

How does Viral contractile tail ejection work?

Answer 3

Binding is done tail ejects DNA, helped by degradation of the peptidoglycan layer.

Question 4

How does viral long flexible tail ejection happen?

Answer 4

Look like a screw and screws down into the membrane- peptidoglycan layer degraded release of DNA.

Question 5

How does viral short ejection system work?

Answer 5

Pushes baseplate through membrane allowing release of DNA.

Question 6

What is the lytic life cycle?

Answer 6

Phage adsorption 
DNA infection 
Hijacking of host machinery 
DNA packing/ virgin assembly 
Cell burst and release of progeny

Question 7

How does lysis occur due to bacteriophages?

Answer 7

Lytic protein accumulation (endolysins &hollins) cause inner and outer membrane disruption making pores. Both membranes then fuse together allowing exit of virions

Question 8

What is the Lysogenic life cycle?

Answer 8

Phage injects DNA into the he host where it combined with the cells DNA to be replicated.

Question 9

How do viruses decide between lytic and lysogenic?

Answer 9

Abundance of bacteria can cause lytic and abundance of phage causes lysogenic. Phages release Arbitrium molecules to signal how many there are of them ( all viruses have different arbitrium molecules)

Question 10

How does Encapsination occur?

Answer 10

Terminase binds viral genome and then binds procapsid portal protein. DNA translocation into the capsid then cleavage of it

Question 11

What are the phases of bacteriophage infection?

Answer 11

Eclipse phase-time between infection and mature virions

Latent phase- time between infection and appearance of symptoms