Which of the following is used in recombinant $DNA$ technology?

In the process of transformation,$DNA$ is coated onto microparticles,which are bombarded using a gene gun. These microparticles are made of:

$Ti-$ plasmids are present in:

Select the option that excludes characteristics applicable to plasmids:
$(a)$. Circular $DNA$
$(b)$. Linear $DNA$
$(c)$. Present in all bacteria
$(d)$. Contain essential genes
$(e)$. Extra chromosomal self-replicating

Common bacteria used in genetic engineering is

Genetic engineering is highly advanced due to the discovery of . . . . . . .