13. Bacterial Genetics (cont.) Flashcards Preview

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Flashcards in 13. Bacterial Genetics (cont.) Deck (30)
1

3 genera of bacteria that can take up naked DNA?

Staph, Strep, Bacillus

2

What is transformation?

Uptake of naked (histone-free) DNA in the form of linear/plasmid DNA

3

Uptake of DNA depends on the expression of _____________

competence proteins

4

Function of competence proteins?

Span cell wall and membrane, recognize specific DNA sequences and permit LINEAR DNA uptake

5

Example of a bacteria that CAN be made competent but is NOT naturally competent?

E. coli

6

3 ways to make a bacteria competent?

CaCl2 treatment => cause transient pore formation

Electroporation

Biolistics => shoot inert beads coated with DNA at high velocity

7

In transformation with plasmid DNA, plasmid may be lost in subsequent generations if there is no ______________

selection pressure

8

Transformation with linear DNA requires what to occur?

Integration into host genome

9

Where will linear DNA integrate into the recipient genome?

At regions w/ high sequence similarity

10

What is required for plasmids to integrate into its host genome?

Special sequences associated with it => insertion sequences

11

What is required for conjugation to occur?

Cell-to-cell contact to form a pilus

12

What is transferred during conjugation?

Plasmid DNA from donor and some of the donor chromosomal DNA

13

The plasmid DNA is also known as what?

Conjugative plasmid/F factor

14

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

15

What is an operon?

DNA sequence that contains 1+ structural genes and the operator controlling their expression

16

During conjugation, what brings the 2 cells to close proximity?

Pilus shortening

17

Where the relaxsosome cut during conjugation?

At origin of transfer

18

Type of DNA that gets transferred during conjugation?

single-stranded DNA ONLY

Becomes dsDNA once it replicates in the new recipient

19

How is an Hfr strain created?

F factor inserts INTO the host chromosome

20

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

21

What is transduction?

Transfer of genes between bacterial/archaeal cells by VIRUSES

22

How is donor DNA carried to the recipient during transduction?

Via an intermediate (bacteriophage)

23

What is a prophage?

Phage DNA incorporated into host chromosome

24

What type of bacteriophage will cause lytic cycle? Lysogenic cycle?

Lytic = virulent phage

Lysogenic = temperate phage

25

What will trigger the transition from lysogeny to lytic phase?

Stress: UV, desiccation, nutrient starvation

26

Difference between lysogenic and lytic phases in terms of the host DNA?

Lytic = host DNA degraded

Lysogenic = host DNA gets donor DNA incorporated

27

What is EAF?

E.coli adherence factor (a huge plasmid)

28

How big is EAF?

100,000 bp

29

What is required for full disease to be caused by pathogenic E.coli?

EAF

30

What 2 things does EAF encode?

bfp (bundle forming pili)

tra operon