The steps involved in the Southern blot test are as follows:
$I.$ $X-ray$ film
$II.$ Electrophoresis
$III.$ Digestion with restriction enzyme
$IV.$ Ethidium bromide
$V.$ Radioactive probe
Choose the option having the correct sequential order of these events.

Which of the following should be chosen for best yield if one has to produce a recombinant protein or enzyme on a large scale,using microbial,plant,animal,or human cells?

How can a recombinant protein be obtained?

Select the option that represents the correct sequence of steps in $r-DNA$ technology.
$(1)$ Insertion of $r-DNA$ into the host
$(2)$ Isolation of $DNA$
$(3)$ Ligation of $DNA$ fragment into the vector
$(4)$ Culturing the host cells in a medium at a large scale and extraction of the desired product
$(5)$ Isolation of the desired $DNA$ fragment
$(6)$ Fragmentation of $DNA$ by restriction endonucleases

Separation of $\text{DNA}$ fragments is done by a technique known as :

If a recombinant $DNA$ bearing a gene for resistance to Ampicillin is transferred into $E. coli$ cells,the host cells become transformed into Ampicillin-resistant cells. What happens when these $E. coli$ are grown on a medium containing Ampicillin?