The Polymerase Chain Reaction $(PCR)$ technique is used for ........

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:

$A$ mixture of fragmented $DNA$ was electrophoresed in an agarose gel. After staining the gel with ethidium bromide,no $DNA$ bands were observed. What could be the reason?

What are bioreactors?

Which one of the following statements is wrong with respect to separation of $DNA$ fragments on gel electrophoresis?

Which of the following range of temperature is required for denaturation,annealing of primer,and primer extension of $PCR$ respectively?