Flashcards in 13. Bacterial Genetics (cont.) Deck (30)
3 genera of bacteria that can take up naked DNA?
Staph, Strep, Bacillus
What is transformation?
Uptake of naked (histone-free) DNA in the form of linear/plasmid DNA
Uptake of DNA depends on the expression of _____________
Function of competence proteins?
Span cell wall and membrane, recognize specific DNA sequences and permit LINEAR DNA uptake
Example of a bacteria that CAN be made competent but is NOT naturally competent?
3 ways to make a bacteria competent?
CaCl2 treatment => cause transient pore formation
Biolistics => shoot inert beads coated with DNA at high velocity
In transformation with plasmid DNA, plasmid may be lost in subsequent generations if there is no ______________
Transformation with linear DNA requires what to occur?
Integration into host genome
Where will linear DNA integrate into the recipient genome?
At regions w/ high sequence similarity
What is required for plasmids to integrate into its host genome?
Special sequences associated with it => insertion sequences
What is required for conjugation to occur?
Cell-to-cell contact to form a pilus
What is transferred during conjugation?
Plasmid DNA from donor and some of the donor chromosomal DNA
The plasmid DNA is also known as what?
Conjugative plasmid/F factor
The conjugative plasmid encodes what 3 things?
About 30 genes in the tra operon ("transfer")
Genes for pillus assembly
Make up the F factor/fertility factor
What is an operon?
DNA sequence that contains 1+ structural genes and the operator controlling their expression
During conjugation, what brings the 2 cells to close proximity?
Where the relaxsosome cut during conjugation?
At origin of transfer
Type of DNA that gets transferred during conjugation?
single-stranded DNA ONLY
Becomes dsDNA once it replicates in the new recipient
How is an Hfr strain created?
F factor inserts INTO the host chromosome
What is an Hfr strain?
Strain that donates its genes with high freq to recipient during conjugation b/c the F factor is INTEGRATED into the bacterial chromosome
What is transduction?
Transfer of genes between bacterial/archaeal cells by VIRUSES
How is donor DNA carried to the recipient during transduction?
Via an intermediate (bacteriophage)
What is a prophage?
Phage DNA incorporated into host chromosome
What type of bacteriophage will cause lytic cycle? Lysogenic cycle?
Lytic = virulent phage
Lysogenic = temperate phage
What will trigger the transition from lysogeny to lytic phase?
Stress: UV, desiccation, nutrient starvation
Difference between lysogenic and lytic phases in terms of the host DNA?
Lytic = host DNA degraded
Lysogenic = host DNA gets donor DNA incorporated
What is EAF?
E.coli adherence factor (a huge plasmid)
How big is EAF?
What is required for full disease to be caused by pathogenic E.coli?