quiz 9 Flashcards
(26 cards)
What is the typical plasmid structure?
circular, double stranded DNA genome residing in a host cell
How do we categorize a plasmid as narrow or broad?
broad if it can infect a bunch of things, narrow if it can’t
Why are plasmids selfish?
They live to replicate themselves
What is a resistance plasmid/what are R factors?
resistance plasmid confers resistance to antibiotics and an R factor is encoded on the genome antibiotic resistance
Whats a transposable element?
segments of DNA that can move itself
What is the R factor presumptive test?
testing for antibiotic resistance, presumptive bc could be caused by something else in the plasmid
Whats conjugation?
direct transfer of DNA from donor cell to recipient cell
How does conjugation occur?
via mating bridge by genetically encoded sex pilus
Which pilus is recognized by QB?
F-plasmid pilus of e.coli
What is the FKW mutant?
mutant that has constitutively expressed sex pills
Whats a bacteriocin?
bactericidal toxins that target cellular processes
Whats the difference between a an antibiotic and a bacteriocin?
A bacteriocin is an antimicrobial peptide that can affect the same strain and an antibiotic has a wider range of infection
What is the plasmid addiction system?
Plasmid encodes immunity to bacteriocin so Host wasnts to keep plasmid so it doesn’t get killed.
Why do we expose the cell to chloroform?
to kill e.coli and leave the colicin
How do we know if a strain produced colicin?
It has a distinct zone of clearing
What was the negative control for colicin?
C600, no colicin or plasmid and is sensitive to colicin
What is the positive control for colicin
MM402, has colicin
What are we searching for in the water?
Fecal contamination in the form of coliform
What are the characteristics of coliform
facultative anaerobes, gram negative rods, ferment lactose w acid and gas
What test are we performing?
multiple tube fermentation test using most probably number of coliform present. Lactose broth is inhibits all bacteria except gram negative rods. Gas production is positive result. Presumptive test. False positives possible, non stringent media because coliforms may be stressed in water and can’t grow in scary places
What is the presumptive water test?
Using laurel lysate, a nonselective broth
What is the BGLB broth?
tests for fecal matter, has bile salts and toxic brilliant green agent
What is EC broth?
is it a coliform, has bile salts
What is homolactive fermentation
2 lactate, 2 ATP
