Genetic Transfer

Question 1

Genetic Transfer is?

Answer 1

the mechanism by which DNA is transferred from a donor to a recipient

Question 2

Genetic Transfer is always _____ and ______

Answer 2

Unidirectional & Partial

Question 3

Once donor DNA is inside the recipient _____ ____- can occur

Answer 3

crossing over

Question 4

3 forms of genetic transfer

Answer 4

Conjugation
Transduction
Transformation

Question 5

Conjugation?

Answer 5

Movement of DNA through a pilus, by action of the F’ fertility factor.

Question 6

Transduction

Answer 6

Usage of a virus vector to deliver the DNA into the target cell

Question 7

Transformation

Answer 7

Direct uptake of naked DNA by the cell. Naturally, this doesn’t happen very readily (you don’t know where that DNA’s been!), so there are some tricks to help the DNA in

Question 8

In bacterial conjugation donor strains contain an additional genetic element, called the?

Answer 8

fertility factor or (F)

Question 9

F(+ or -) strain mate with F(+ or -) strains.

Answer 9

F+ , F-

Question 10

DNA transfer occurs unidirectionally from?

Answer 10

F+ to the F-

Question 11

The F’ fertility factor can replicate both through _____ & _____ _____ _____ replication

Answer 11

rolling-circle and normal double-stranded (theta-structure) replication

Question 12

Key areas on the F’ site include (4)

Answer 12

oriT
Tra genes
Inception sequences
oriV

Question 13

F+ cells do not attach to other?

Answer 13

F+ cells, due to the presence of two proteins in F+ cells:

Question 14

An Hfr (high frequency of recombination) strain occurs when?

Answer 14

the F’ factor becomes integrated into the E. coli host chromosome, due to the presence of the insertion sequences.

Question 15

Transformation direct uptake of DNA ‘tricks’ to allow entry? (2)

Answer 15

Electro-competence

Calcium competence

Question 16

Transduction (also known as transfection): Usage of a?

Answer 16

Usage of a virus vector to deliver the DNA into the target cell

Question 17

A bacteriophage or phage is a?

Answer 17

virus that infects bacteria.

Question 18

General Steps Of The Lytic Cycle? (5)

Answer 18

1) Attachment of T4 to receptors on E. coli cell wall.
2) Penetration of the cell wall by tail core. Inject DNA into host.
3) E. coli DNA is hydrolyzed. Phage DNA directs biosynthesis of viral parts using the host cell’s machinery.
4) The phages mature as the parts are assembled.
5) Lyses of E. coli and release of the new phages.

Question 19

Regulatory genes products are responsible for?

Answer 19

regulation the transcription (turn on or off the transcription of other genes)

Question 20

Regulatory cascade, is?

Answer 20

the regulation performed by regulatory genes

Question 21

Prophage

Answer 21

state of the phage in a lysogen in which the phage DNA is integrated into the chromosomal DNA of the bacterium or replicates as plasmid

Question 22

Lysogen

Answer 22

a strain of bacteria that harbors a prophage

Question 23

Lysogenic cycle series of?

Answer 23

series of events that follow infection by a bacteriophage and culminate in the formation of stable prophage

Question 24

Lysogenic phage

Answer 24

is a phage which is capable of entering a prophage state

Question 25

General Steps of The Lysogenic Cycle

Answer 25

1) Phage attaches to E. coli and injects DNA.
2) Phage circularizes and can enter either the lytic or the lysogenic cycle.
3) In the lysogenic cycle the circular phage DNA recombines with E. coli DNA and the phage DNA is now called prophage.
4) E. coli undergoes cell division, copying prophage and passing to daughter.
With more divisions there are more cells with the prophage.
5) The prophage may exit the chromosome and start a lytic cycle at any time.
6) The lytic cycle would occur as previously described.

Question 26

Phage Transduction?

Answer 26

A genetic exchange in which bacteriophages carry bacterial genes from one host cell to another.

Question 27

Two classes of transduction: (2)

Answer 27

Generalized transduction

Specialized transduction

Question 28

The Steps Of General Transduction

Answer 28

1) A phage attaches to cell wall of bacterium and injects DNA.
2) The bacterial chromosome is broken down and biosynthesis of phage DNA and protein occurs.
3) Sometimes bacterial DNA can be packaged into the virus instead of phage DNA.
This phage is defective (can’t destroy another host cell) because it does not carry its own genetic material.
4) The cell lyses, releasing viruses.
5) The phage carrying bacterial DNA infects another cell.
6) Crossing over between donor and recipient DNA can occur producing a recombinant cell.

Question 29

Specialized Transduction

Answer 29

1) Remember that in the lysogenic cycle, phage DNA only exist as a prophage integrated in the bacterial chromosome)
2) Occasionally when the prophage exits it can take adjacent bacterial genes with it.
3) The phage DNA directs synthesis of new phages.
The phage particles carry phage DNA and bacterial DNA.
4) The cell lyses, releasing the phages.
5) A phage carrying bacterial DNA infects another cell.
6) The joined phage and bacterial DNA circularize.
7) Along with the prophage, bacterial DNA integrates with the recipient chromosome by a cross over event.
This forms a recombinant cell.