Question

As a general principle, in order to validate results in scientific experiments, scientists use controls. A control is a group that is designed to demonstrate that the results/changes observed in an experiment were because of the procedure you performed. It sets a baseline value with which the scientist can compare with experimental sample and interpret results, as was demonstrated in the previous question. In this question, we are asking you to describe the control experiments, using the same transformation protocol, with pGRN plasmid.

You want to test whether the E. coli cells were viable (alive).How would you test this?Consider the following:

(a) do you add the plasmid to the cells?

(b) what plate do you use – NA or NA-AMP and

(c) do you use visible light or UV light?

Answer 1

a) No, we do not add plasmid to the cells. Control plate has only the competant cells (i.e without the plasmid) to check the viability of competant cells.

b)We use NA plates for controls as competant cells can grow only on plain Nutrient agar plate but not on NA Amp as they do not contain the plasmid that has resistance for ampicilin.

c) We use visible light to check large number of colonies on NA plate. This shows that the E.coli cells are viable and so it is considered to be a 'Positive Control'