Discuss briefly how a probe is used in molecular diagnostics.

In gel electrophoresis,at which end is the sample loaded?

Consider the following statements:
$I.$ In microinjection method,foreign $DNA$ is directly injected into the nucleus of an animal cell or plant cell by using microneedles or micropipettes.
$II.$ Microinjection method is used in oocytes,eggs,and embryos.
$III.$ Electroporation is the formation of temporary pores in the plasma membrane of a host cell by using lysozyme or calcium chloride.
$IV.$ In chemical-mediated gene transfer method,certain chemicals such as $CO_{2}$ help foreign $DNA$ to enter the host cell.
Which of the statements given above are correct?

Identify the labels $X$,$Y$,and $Z$ in the given diagram representing the process of recombinant $DNA$ technology.

$A$ recombinant $DNA$ molecule was created by ligating a gene to a plasmid vector. By mistake,an exonuclease was added to the tube containing the recombinant $DNA$. How does this affect the next step in the experiment,i.e.,bacterial transformation?

Main steps in the formation of Recombinant $DNA$ are given below. Arrange these steps in a correct sequence.
$A$. Insertion of recombinant $DNA$ into the host cell
$B$. Cutting of $DNA$ at specific location by restriction enzyme
$C$. Isolation of desired $DNA$ fragment
$D$. Amplification of gene of interest using $PCR$
Choose the correct answer from the options given below: