Question

What restriction enzymes produced the two sequences below? If the sequences below are hybridized and ligated, explain why it would not be possible to cut the new sequence with either of the original restriction enzymes. a)5’—T 3’—AGATC b) CTAGT—3’ A—5’

Answer 1

In rDNA technology, restriction enzymes are used to cut the cloning vector, and the same enzyme is used to cut the desired DNA segment. Cutting both the DNA molecules with the same enzyme provides cohesive ends that are easily stuck together using ligase.

The given sequences are produced by Spe I and Xba I restriction enzymes.

Spe I

5’-A   CTAGT-3’

3’- TGATC   T – 5’

Xba I

5’- T   CTAGA – 3’

3’ – AGATC T – 5’

If the below given sequences are ligated, their restriction site changes and hence cannot be cut by either of the two enzymes.