1.8 The viruses Flashcards
Characteristics of Virus
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
Host range of Viruses?
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.
Transmission of Viruses?
Transmission may occur through direct contact, indirect contact with fomites, or through a mechanical or biological vector.
Prophage
the phage DNA that is incorporated in to the bacterial chromosome
Lysogen
bacterial cell that contains a prophage
Lysogenic or phage conversion
change in the host cell’s properties due to the presence of prophage gene(s)
Induction
events trigger the excision of the prophage
What is Transduction?
Transfer of bacterial genes from one cell to another via a phage
Generalized Transduction
transfer of random DNA fragments through accidental packaging in a virulent phage capsid
Specialized transduction
transfer of bacterial genes due to imprecise excision of a prophage followed by incorporation into a phage capsid