A few quick clarifications!

[cbf]

Does the highest m/z always = molar mass on mass spectrum as sometimes i notice there is one small peak after the molar mass m/z because of Carbon 13? And could some please outline the main process of PCR? Thanks

[Tonychet2]

usually, yes watch out for m/z ratio of 2 however and although out of the course the highest peak may be 100% completely fragmented so it does not equal the parent molecule

[soccerboi]

For the exam, yes the highest m/z usually is the molar mass, and disregard those little peaks, i think they're due to isotopic behaviors or something.
PCR is used to amplify the number of DNA fragments. It is a DNA replication process that involves alternatively heating and cooling a DNA sample. 3 steps, denaturation where hydrogen bonds are broken, annealing (cooling) and elongation (heated again). Complementary base pairs are added to the single DNA strands. This reaction is catalysed by the enzyme polymerase. Each heating and cooling cycle doubles the number of copies of each DNA.
Hope that helps

[k0k0p0p]

Just a slight side note, there is a seriously awesome song on Youtube about PCR. It is called 'the PCR song' (I think) and is actually an advertisement for a PCR machine. It details the process and reason for PCR and is incredibly helpful! Also really easy to remember!

[cbf]

thanks soccerboi, do you think thats as much as we'll need in the exam?