In genetic engineering,restriction enzymes are used to create:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: When a particular restriction enzyme cuts a strand of $DNA$,overhanging stretches or sticky ends are formed.
Reason $(R)$: Some restriction enzymes cut the strand of $DNA$ a little away from the centre of the palindromic site.
In the light of the above statements,choose the correct answer from the options given below:

Restriction endonucleases are:

$pBR322$ contains the recognition sites for which of the following endonucleases at the $amp^R$ site?

In the $PCR$ technique,the amplification of a $DNA$ segment is carried out by which enzyme?

What should a cloning vector $NOT$ possess?