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

Identify the desirable characteristics for a plasmid used in $rDNA$ technology from the following.
$A$. Ability to multiply and express outside the host in a bioreactor.
$B$. $A$ highly active promoter
$C$. $A$ site at which replication can be initiated
$D$. One or more identifiable marker genes
$E$. One or more unique restriction sites.

The gene whose expression helps to identify the transformed cell is known as........

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

How are antibiotics used in genetic engineering?

The chemical knives of $DNA$ are: