What is the first step in the Southern Blotting technique?

Spooling is:

The blue and white selectable markers have been developed which differentiate recombinant colonies from non-recombinant colonies on the basis of their ability to produce colour in the presence of a chromogenic substrate.
Given below are two statements about this method :
Statement-$I$ : The blue coloured colonies have $\text{DNA}$ insert in the plasmid and they are identified as recombinant colonies.
Statement-$II$ : The colonies without blue colour have $\text{DNA}$ insert in the plasmid and are identified as recombinant colonies.
In the light of the above statements,choose the most appropriate answer from the options given below:

Production of a human protein in bacteria by genetic engineering is possible because

Which one of the following statements is correct regarding gel electrophoresis?

The stirrer in a stirred-tank bioreactor facilitates: