What is a control used for in molecular biology?

Question

what is a control used for in molecular biology

Answer 1

In molecular biology the control is used to ensure that either you actually had DNA in the sample or that your protocol is working properly.

For example, if you wanted to extract some DNA from a species and run it on a gel to see if you had actually been successful, you would probably run control DNA in one lane of the gel.  The control would be a sample you absolutely knew contained DNA.  Then, if your control showed up on the gel but your samples did not, then you would know that the gel ran fine, but that you were not successful in extracting DNA from your samples.  Without the control, you wouldn't know if it was your extraction or gel protocol that failed.

Answer 2

A control - unless you provide more specific details - is used in all sciences during experiments.  It is the baseline for the experiments.  For example, to determine which antibiotic was most effective in a culture dish of a specific type of bacteria.  You would have to have a culture dish with no antibiotic added to compare your others to.  That one would be your control.