Question

Que .

When phage infect a bacterial cell, they typically have a temporal program of gene expression, i.e., they express particular genes at particular times. What are two regulatory mechanisms phage use to control their gene expression?

Please state clearly each mechanism and provide detail explanation.

Answer 1

A bacteriophage can use two mechanisms for its host cell
a) In the lytic cycle process the phage attack and captures bacteria and produces the progeny/ multiple copies of phage in large number.

b) The next method is lysogenic pathway in which the phage chromosome are inserted into host cell and they replicate within the host cell (bacterial cell)

a) Lytic cycle

1. Attaching phase in this virus attach itself to the E.coli
2. Insertion phase in this virus will inject either this DNA or RNA into the E.coli cell/host
3. Synthesis phase in this the virus DNA or RNA will destroy the host/ E.coli DNA and start to produce copies of their own genetic material
4. Growing phase in this stage new viruses are formed and the virus DNA and the capsids are made new using host (E.coli) DNA
5. The releasing phase in this stage the new viruses formed will be released and leave the host cell (E.coli) and then capture new cells or host.

b) Lysogenic cycle

The actual mechanism start after attaching phase, insertion phase, virus remain inside the host cell(E.coli) without replication and it eventually destroy the host DNA .This is latent stage. If there is requirement of new viruses any time the original virus may start the lytic cycle.
Example:
Herpes simplex virus