Chapter 3: Bacterial Sex Genetics

Question 1

What are the four ways that bacteria can exchange genetic fragments?

Answer 1

Transformation
Transduction
Conjugation
Transposon

Question 2

The process of transformation

Answer 2

Naked DNA fragments from one bacterium released during lysis, bind to the cell wall of another bacterium

Recipient bacterium must be competent

Question 3

Competent

Answer 3

Structures on the bacteria cell wall that can bind the DNA and take it up intracellularly
Recipient is usually of the same species as the donor

Question 4

Transduction

Answer 4

Bacteriophage carries a piece of bacterial DNA from one bacterium to another

Question 5

Virulent phages

Answer 5

infect bacteria, reproduce, then lysis and kill bacteria

Generalized transduction

Question 6

Temparate phages

Answer 6

Do not immediately lyse bacteria
Do not undergo transcription
DNA becomes incorporated into the bacterial chromosome
DNA waits for signal to become active

Specialized transduction

Question 7

Prophage

Answer 7

Integrated temparate phage genome

Question 8

Lysogenic

Answer 8

Bacteria that have a prophage integrated into their chromosome

Question 9

Lysogenic immunity

Answer 9

Ability of an integrated bacteriophage to block a subsequent infection by a similar phage

Question 10

Conjugation

Answer 10

DNA exchanged by cell-to-cell contact

Major mechanism for transfer of antibiotic resistance

Question 11

For conjugation to occur, one bacterium must have what? What will it form?

Answer 11

self-transmissible plasmid called an F plasmid

F plasmid has a gene that encodes enzymes and proteins that form the sex pilus

Question 12

What is an Hfr cell?

Answer 12

F plasmid is integrated into the bacterial chromosome

Question 13

What can result from an Hfr cell?

Answer 13

(1) Entire bacterial chromosome will transfer from the Hfr cell to the recipient cell
(2) integrated F plasmid in the Hfr cell may be excised at a different site from that of integration –>F plasmid that has a segment of chromosomal DNA (F’ plasmid)

Question 14

What is analogous to specialized transduction and why?

Answer 14

F’ conjugation because in both situations a nearby segment of chromosomal DNA is picked up accidentally and can be transferred to other bacterial cells

Question 15

Transposons

Answer 15

Mobile genetic elements
can insert into DNA w/o DNA homology
Can spread drug resistance strains rapidly