Which of the following is associated with genetic engineering?

$A$ : $Pst I$ generates single-stranded overhanging stretches in $DNA$ after digestion that facilitate ligation.
$R$ : These short extensions can form hydrogen bonds with their complementary counterparts,which are then sealed by $DNA$ ligase to form phosphodiester bonds.

What is the function of restriction endonucleases?

Which enzyme removes nucleotides from the ends of $DNA$?

In genetic engineering,to which part of the bacteria is the human $DNA$ joined to produce a product?

The restriction enzyme responsible for the cleavage of the following sequence is:
$5^{\prime}-G-T-C-G-A-C-3^{\prime}$
$3^{\prime}-C-A-G-C-T-G-5^{\prime}$