What are the differences between a prophage and a provirus?
A prophage is created when bacteriophage DNA becomes incorporated into the bacterial host's DNA (Lysogenic cycle). Once established, virus can remain dormant for long periods. Each time bacterium divides, prophage is copied and becomes part of progeny bacterium. Phage DNA codes for viral proteins to assemble new temperate phages which mature and are released through cell lysis. A provirus is formed by retroviral-infected cells, after reverse transcription occurs, the viral DNA in itself into a..
Cont. with provirus:
..host's chromosome, a provirus that can remain there indefinitely. When infected cells divide, the provirus is replicated along with the rest of the host chromosome and viral information is passed to progeny host cells. Unlike prophages, this provirus cannot be excised from the chromosome.
How can a bacteriophage affect the pathogenicity of a microorganisms?
Toxic effects of some bacteria are caused by the prophages they contain. C.botulinum contains a prophage that codes for production of toxin causing botulism. This Clostridium species would not be pathogenic otherwise.
What is a plasmid?
An extra-chromosomal ring of DNA that's not required for bacterial metabolism.