Lecture--Chapter 9 Flashcards
Bacteria are usually ____.
haploid
Bacteria have easier to identify _____ than in eukaryotes.
loss-of-function mutations
Bacteria reproduce ____ by ____.
asexually; binary fission
a collection of strains that share stable genetic properties and evolve as a group
a bacterial species
Genetic crosses cannot be used in the genetic analysis of ____.
bacterial species
Transfer of _____ occurs between bacteria, thereby enhancing genetic diversity.
bacterial DNA
Transfer of genetic material from one bacterium to another can occur in three ways:
- conjugation
- transduction
- transformation
direct transfer of DNA from one cell to another
conjugation
viral mediated transfer of DNA between bacteria
transduction
uptake of DNA from the environment
transformation
showed genetic transfer in bacteria in 1946
Joshua Lederberg and Edward Tatum
Studied nutritional growth requirements of different strains of E.coli:
Joshua Lederberg and Edward Tatum
bio- met- thr+ leu+ thi+:
required biotin, methionine
bio+ met+ thr- leu- thi-:
required threonine, leucine, thiamine
showed in 1950 that genetic transfer in bacteria requires physical contact:
Bernard Davis
Process that David used:
- filter that restricted movement of intact bacteria
2. after incubation, moved to complete media
During conjugation, a special plasmid that is required:
F factor (fertility factor)
Which genes does the F factor plasmid carry for conjugation?
- Pilus proteins
2. Relaxosome proteins
A protein tube connecting the cytoplasm of bacterial cells:
pilus proteins
Interact with the DNA during conjugation, move a copy through the pilus
relaxosome proteins
F factor genes–origin of transfer:
oriT
Conjugation events: An F+ bacterium has ____ that produces pili.
an F factor plasmid
Conjugation events: When a _____ encounters an F- bacterium, it attaches and pulls it close to the F+ bacterium.
pilus
Conjugation events: The _____ cuts 1 strand of the F plasmid and directs the cut end to the _____.
relaxosome; pilus
Conjugation events: The ______ pump the strand through the _____ to the F- cell.
exporter proteins; pilus
Conjugation events: The recipient cell replicates second strand, becoming an _______.
F+ cell
High frequency recombination strains:
Hfr strains
The ____ integrates the genome of the bacterium.
F factor
During conjugation a portion of the ____ is transferred to recipient cells.
bacterial genome
Used Hfr strains to begin mapping the E. coli genome in the 1950’s:
Elie Wollman and Francois Jacob