Draw a schematic diagram of the E. coli cloning vector pBR322 and mark the following in it:

(a) ori

(b) rop

(c) ampicillin resistance gene

(d) tetracycline resistance gene

(e) restriction site BamHI

(f) restriction site EcoRI

OR

(a) Draw schematic diagrams of segments of a vector and a foreign DNA with the sequence of nucleotides recognised by EcoRI.

(b) Draw the vector DNA segment and foreign DNA segments after the action of EcoRI and label the sticky ends produced.

The labeled schematic diagram of pBR322 is shown below:

_• EcoR1 and BamHl- is restriction enzyme

_• Ori and rop genes

_• amp and tet - antibiotic resistant gene

OR

(a): Below is the diagram of segments of vector and a foreign DNA with the sequence of nucleotides recognised by EcoR1.

(b):

•Restriction enzymes cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands.

•This leaves single stranded portions at the ends. There are overhanging stretches called sticky ends on each strand.

•These are named so because they form hydrogen bonds with their complementary cut counterparts.

•This stickiness of the ends facilitates the action of the enzyme DNA ligase.