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Flashcards in Bacterial genetics Deck (19):
1

Bacterial genetics - transformation / aka

Ability to take up naked DNA (from cell lysis) from environment / AKA competence

2

transformation (competence) - which bacteria?

many bacteria --> especially S. pneumoniae, H. influenzae type B, Neisseria

3

transformation (competence) - which DNA is used

any DNA can be used

4

how to avoid transformation in medium

add deoxyribonuclease to environment --> to degrade naked DNA

5

bacterial Conjunction - types

1. F+ x F-
2. Hfr x F-

6

F+ bacteria vs F- bacteria?

F+: bacterial with plasmid contains genes required for sex pilus and conjugation
F-: bacterial without plasmid contains genes required for sex pilus and conjugation

7

F+ x F- conjunction?

sex pilus on F+ bacterium contacts F- bacterium. A SINGLE strand of plasmid DNA is transferred across the conjugal bridge (aka the mating bridge)

8

F+ x F- conjunction - what is transferred and what is not transferred

A SINGLE strand of plasmid DNA is transferred
NO TRANFER OF CHROMOSOMAL DNA

9

F+ x F- conjunction - transfer across

the conjugal bridge (aka the mating bridge)

10

Hfr bacteria?

F+ plasmid can become incorporated into bacterial chromosomal DNA, termed high-frequency recombination (Hfr) cell

11

Hfr x F- conjugation?

replication of incorporated DNA may include some flaking chromosomal DNA --> transfer of plasmid and chromosomal

12

bacterial transposition?

segment of DNA (transposon) that can jump (excision and reintergation), can trafer genes from plasmid to chromosome and vise versra. When excision occurs, may include some flanking chromosomal DNA, which can incorporated into a plasmid transferred to another bacterium

13

tranfer of a gene from a bacterium to another bacterium through transposition (examples)

vanA gene from vancomycin-resistant Enterococcus to S. aureus

14

bacterial transduction - types

1. Generalized
2. Specialized

15

bacterial generelized transduction?

a packaging event. Lytic phage infects bacterium, leading to cleavage of bacterial DNA. Parts of bacterial dna may become packaged in viral capsid. Phage infects another bacterium, transferring these genes

16

bacterial specialized transduction?

an excision event. Lysogenic phage infects bacterium. viral DNA incorporates into bacterial chromosome. When phage DNA is excised, flanking bacterial genes may be excised with it. DNA is packaged into phage viral capsid and can infect another bacterium

17

bacterial specialized transduction - genes for the following bacterial toxins are encoded in lysogenic phage

mnemonic: ABCDE
1. shigA-like toxin
2. Botilinum toxin (certain strains)
3. Cholera toxin
4. Diphteria oxin
5. Erytrhogenic toxin of streptococcus pyogenes

18

bacterial specialized vs generalized transduction according to virus

specialized --> lysogenic phase
generalized --> lytic phase

19

F+ x F- vs Hfr x F- conjugation according to transfer

F+ x F- --> transfer single strand of plasmid DNA, no chromosomes
Hfr x F- --> tranfer of plasmid and chromosomal genes