What is chimeric $DNA$?

Transfer of any gene into a completely different organism can be done through

The critical research areas of biotechnology are:
$I$. Providing the best catalyst as an improved organism,usually a microbe or pure enzyme.
$II$. Creating optimal conditions through engineering for a catalyst to act.
$III$. Downstream processing technologies.
$IV$. Multiple Ovulation Embryo Transfer Technology $(MOET)$.
Which of the statements given above are correct?

When did Cohen and Boyer complete the construction of the first $r-DNA$ by isolating an antibiotic resistance gene?

What is the origin of replication $(ori)$?

The number of copies of $DNA$ inserted in a host is determined by this sequence: