PCR reaction is used to amplify DNA fragment. Each reaction requires a DNA template, buffer, dNTP mix and a unique pair of primers, one ''forward'' primer and one ''reverse'' primer. The DNA polymerase should be added last to the reaction, just before starting the PCR programme.
My question is, why is DNA polymerase added right before the PCR starts? Is it because it can begin to amplify DNA before adding the reaction to the thermocycler? How could it amplify the DNA when the DNA is not denaturated until added to the thermocycler?