13. Bacterial Genetics (cont.)

Question 1

3 genera of bacteria that can take up naked DNA?

Answer 1

Staph, Strep, Bacillus

Question 2

What is transformation?

Answer 2

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

Question 3

Uptake of DNA depends on the expression of _____________

Answer 3

competence proteins

Question 4

Function of competence proteins?

Answer 4

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

Question 5

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

Answer 5

E. coli

Question 6

3 ways to make a bacteria competent?

Answer 6

CaCl2 treatment => cause transient pore formation

Electroporation

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

Question 7

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

Answer 7

selection pressure

Question 8

Transformation with linear DNA requires what to occur?

Answer 8

Integration into host genome

Question 9

Where will linear DNA integrate into the recipient genome?

Answer 9

At regions w/ high sequence similarity

Question 10

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

Answer 10

Special sequences associated with it => insertion sequences

Question 11

What is required for conjugation to occur?

Answer 11

Cell-to-cell contact to form a pilus

Question 12

What is transferred during conjugation?

Answer 12

Plasmid DNA from donor and some of the donor chromosomal DNA

Question 13

The plasmid DNA is also known as what?

Answer 13

Conjugative plasmid/F factor

Question 14

The conjugative plasmid encodes what 3 things?

Answer 14

About 30 genes in the tra operon (“transfer”)

Genes for pillus assembly

Make up the F factor/fertility factor

Question 15

What is an operon?

Answer 15

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

Question 16

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

Answer 16

Pilus shortening

Question 17

Where the relaxsosome cut during conjugation?

Answer 17

At origin of transfer

Question 18

Type of DNA that gets transferred during conjugation?

Answer 18

single-stranded DNA ONLY

Becomes dsDNA once it replicates in the new recipient

Question 19

How is an Hfr strain created?

Answer 19

F factor inserts INTO the host chromosome

Question 20

What is an Hfr strain?

Answer 20

Strain that donates its genes with high freq to recipient during conjugation b/c the F factor is INTEGRATED into the bacterial chromosome

Question 21

What is transduction?

Answer 21

Transfer of genes between bacterial/archaeal cells by VIRUSES

Question 22

How is donor DNA carried to the recipient during transduction?

Answer 22

Via an intermediate (bacteriophage)

Question 23

What is a prophage?

Answer 23

Phage DNA incorporated into host chromosome

Question 24

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

Answer 24

Lytic = virulent phage

Lysogenic = temperate phage

Question 25

What will trigger the transition from lysogeny to lytic phase?

Answer 25

Stress: UV, desiccation, nutrient starvation

Question 26

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

Answer 26

Lytic = host DNA degraded

Lysogenic = host DNA gets donor DNA incorporated

Question 27

What is EAF?

Answer 27

E.coli adherence factor (a huge plasmid)

Question 28

How big is EAF?

Answer 28

100,000 bp

Question 29

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

Answer 29

EAF

Question 30

What 2 things does EAF encode?

Answer 30

bfp (bundle forming pili)

tra operon