Q1 Draw a flowchart with simple diagrams to show the first two cycles of PCR, starting with onedoublestrandedDNA molecule. Colours will help you identify the different strands of DNA.Q2 The enzyme polymerase is only added during the first PCR cycle, but continues to catalyse DNAreplication through many cycles. Considering the treatment of the DNA during PCR, what property doespolymerase show that is unusual for an enzyme?Q3 What feature of a DNA molecule ensures accurate replication of the strands during each PCR cycle?Q4 Explain how PCR has revolutionised criminal investigations.Q5 The graph in Figure 1 shows the potential number of copies of DNA produced during PCR. Use yourunderstanding of the process to explain how so many copies can be produced in relatively few cycles.

Q1 The restriction enzymes in the coloured tubes are suspended in a buffer solution. Why is this important?Q2 Why are the reaction tubes containing enzyme and DNA incubated at 37 °C?Q3 Do the DNA fragments move towards the anode (positiveelectrode) or the cathode (negative electrode)?Q4 What is the charge on a DNA fragment?Q5 At which end of the gel are the smallest DNA fragments?Explain your answer.Q6 On Figure 2:a circle any fragments of the EcoRI single digest that donot have a BamHI recognition siteb circle any fragments in the double digest that have beenproduced as a result of the DNA being cut by one enzymeand then the other enzyme.

Figure 2 A gel produced from DNA cut withEcoRI and BamHI