1.8 The viruses

Question 1

Characteristics of Virus

Answer 1

Acellular
Obligate intracellular parasites
Only infect specific hosts and cells
Genome consist of DNA or RNA
Has a protein coat called a capsid and sometimes an envelope
Uses host cell’s machinery to replicate

Question 2

Host range of Viruses?

Answer 2

Viruses are only able to enter specific cell types in specific species
The host range is determined by the ability of viral ligands to bind to specific cell receptors.

Question 3

Transmission of Viruses?

Answer 3

Transmission may occur through direct contact, indirect contact with fomites, or through a mechanical or biological vector.

Question 4

Prophage

Answer 4

the phage DNA that is incorporated in to the bacterial chromosome

Question 5

Lysogen

Answer 5

bacterial cell that contains a prophage

Question 6

Lysogenic or phage conversion

Answer 6

change in the host cell’s properties due to the presence of prophage gene(s)

Question 7

Induction

Answer 7

events trigger the excision of the prophage

Question 8

What is Transduction?

Answer 8

Transfer of bacterial genes from one cell to another via a phage

Question 9

Generalized Transduction

Answer 9

transfer of random DNA fragments through accidental packaging in a virulent phage capsid

Question 10

Specialized transduction

Answer 10

transfer of bacterial genes due to imprecise excision of a prophage followed by incorporation into a phage capsid