Vectors 2:Bacteriophages

Question 1

How are complete λ bacteriophages formed?

Answer 1

Bacteriophage λ undergoes either lytic replication or lysogeny following the infection of E. coli
Lytic replication results in cell death of E. coli and the formation of clear plaques on a cell lawn
The heads and tails of λ systems are self-assembling proteins
The addition of DNA containing COS sites ate the correct spacing (43-53 kb) allows spontaneous formation of a complete λ phage

Question 2

Describe λ phage vectors

Answer 2

Have a central stuffer fragment which is replaced by DNA to be cloned

Question 3

What is the central stuffer?

Answer 3

Contains genes used in the lysogenic life cycle

Question 4

What type of DNA can be taken up by a λ phage vector?

Answer 4

Linear DNA

Question 5

How does the DNA fragment fit into the vector?

Answer 5

It replaces a part of the phage

Question 6

How efficient is the transformation?

Answer 6

Very efficient (10^9 μ^-1) and is constant with increasing insert size