Virus genetics Flashcards
Viruses are infectious particles conssiting of what molecule?
nucleic acid molecules
The nucleic acid molecules are enclosed by what?
Capsid which consist largely or entirely of protein
the viral chromosomes does what to cell’s metabolism?
Redirects it to produce new viruses
what is lysis?
breaking open of host cell thus releasing bacteriophages or mature virus particles that can initiate new round of infection
Viruses have no metabolism of their own thus are what?
depended on host; depended parasite
Are viruses living? why or why not?
No because in the absence of their host they are biologically inert as many other large molecules
how are bacteriophages (bacteria infected by viruses) detected?
By plaques (clear spots) on a lawn of bacteria on a culture plate.
what do plaques mark?
Where the spot where single phage particles had multiplied with the resulting lysis of the bacteria in the area.
How is a mutant phage detected?
A mutant phage can produce progeny under certain permissive conditions, is detected by its inability to do so under other restrictive conditions on which the wild type phage is viable.
what are the general steps of a life cycle of a virus?
1) Virus particle adsorption to host cell
2) Injection of viral chromosome into the host cell
3) Replication of viral chromosome
4) Encapsulation of viral chromosomes by protective coat
5) Host cell Lysis releasing mature virus particles
what does it mean by viruses are subject to complementation?
Simulataneous infection of bacterium by two different mutant varieties of a phage may yield progeny under conditions in which neither variety by itself can reproduce.
if complementation of viruses occur what does this mean?
Than each mutant phage must have supplied a function that the other could could not supply. Thus suchvmutant is said to belong to a different complementation group.
Are viral chromosomes subject to recombination? why or why not?
Yes; occurs when single cell is simultaneously infected by two mutant strains of a virus.
If viral recombimation occurs how is it the same or different than recombination or eukaryotes or bacteria?
-The dynamics of viral recombination differ from those in eukaryotes or bacteria because the viral chromosome undergoes recombination through several rounds pf DNA replication thatoccur during the viral life cycle
recomination of viral progeny consist of what?
many if not all of possible recombination types
