Write down four characters of viruses.
- Virus are non-cellular infectious entities
- They contain either RNA or DNA, normally encased in the proteinaceous coat.
- They reproduce only in living cells.
- Viruses utilize the biosynthetic machinery of the host for its own synthesis.
Differentiate between virion and prions.
The complete, mature and infectious virus particle is known as virion. The virions are composed of a central core of nucleic acid, either DNA or RNA, surrounded by protein coat. Prions are composed of protein only that contains the information that codes for their own replication. Prions are responsible for mad cow infection and mysterious brain infection in man.
What is lysogenic cycle of phage?
In some cases viral DNA, instead of taking over the control of host’s machinery, becomes incorporated into the bacterial chromosome. Phage in this state is called prophage and this process is known as lysogeny or lysogenic cycle. Viral DNA being the part of bacterial chromosome passes to each daughter cell in all successive generations.
Differentiate between lytic and temperate phage.
The phage which causes lysis of a bacterium is called lytic or virulent phage. The phage which causes fysogeny is called temperate (lysogenic) or avirulent phage.
What are symptoms of small pox?
In small pox, raised fluid-filled vesicles are formed on the body which become pustule (pimple or blister) later on and form pitted scars, the pocks.
Differentiate between lysogeny and induction.
In some cases viral DNA, instead of taking over the control of host’s.