Bacterial and Viral Genetics Flashcards
4 types of bacterial genetics?
1) Transformation
2) Conjugation
3) Transposition
4) Transduction
Transformation?
Ability to take up naked DNA from lysed cells from environment (also known as “competence”)
Which bacteria undergo transformation?
SHiN
What happens if you add deoxyribonuclease to environment with naked DNA in medium?
Naked DNA will degrade and no transformation will occur
F+ plasmid?
Contains genes required for sex pilus and conjugation
F- bacteria?
Bacteria without the plasmid
What is a plasmid?
dsDNA
F+ x F-?
Plasmid is replicated and transferred thru pilus from F+ to F- bacteria (NO transfer of Chr genes occurs)
High frequency recombination (Hfr) cell?
F+ plasmid becomes incorporated into bacterial Chr DNA
Hfr x F-?
Trasnfer of plasmid and Chr genes occurs
Conjugation?
F+ x F- and Hfr x F-
Transposition?
Segment of DNA that can “jump” (excision and reintegration) from one location to another, can trasnsfer genes from plasmid to Chr and vice versa
Transduction?
1) Generalized
2) Specialized
“Packaging” event?
Generalized transduction
“Excision” event?
Specialized transduction
Uses lytic phage?
Generalized
Uses lysogenic phage?
Specialized
Generalized?
Lytic phage infects bacterium leading to cleavage of bacterial DNA, bacterial DNA is packaged in viral capsid and phage then infects another bacterium transferring these genes
Specialized?
Lysogenic phage infects bacterium and viral DNA incorporates into bacterial Chr, phage DNA is excised along with some bacterial DNA, mixed DNA is packaged into viral capsid and infects another bacterium
5 bacterial toxins encoded in a lysogenic phage?
ShigA-like toxin Botulinum toxin Cholera toxin Diphtheria toxin Erythrogenic toxin of GAS
Recombination?
Exchange of genes bt 2 Chrs by crossing over within regions of significant base sequence homology
Reassortment?
Viruses with segmented genomes exchange segments–causes worldwide influenza pandemics
Complementation?
When 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein
How does complementation produce a functional protein?
The nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses
Phenotypic mixing?
Occurs with simultaneous infection of cell with 2 viruses
MOA of phenotypic mixing?
1) Genome of virus A is coated with surface proteins of virus B producing a pseudovirion
2) Type B protein coat determines infectivity
3) However, progeny have type A coat that is encoded by its type A genetic material
