1. 1,000,000 1,000,000,000 PCR cycles 20 40 30 Theorectical yield Actual yield “Plateau effect” No. of DNA copies How much DNA amplification has occurred?

2. How do scientists analyse these PCR products?

3. Agarose Gel Electrophoresis Separates DNA fragments according to their size

4. Step 1 – Agarose is added to buffer and heated to 95ºC (to melt it). After cooling, it is poured into a pre-prepared casting tray Step 2 – a comb is inserted immediately to create wells for loading the samples Step 3 – the gel is left to set Step 4 – the comb is removed slowly (see set of wells that have been created) Making Agarose Gel

5. Agarose gel Well 1 Well 2 Well 3 Well 4 Well 5 Making Agarose Gel A fluorophore (DNA SafeView) is added to the gel. This intercalates with the DNA & fluoresces when excited by UV light

6. Agarose gel Loading DNA samples

7. Agarose gel Loading DNA samples

8. Separating the DNA Fragments After the samples are loaded into the wells, an electric current is applied across the gel and the gel is “run”

9. __++ Separating the DNA Fragments

10. __++

11. __++

12. Visualising DNA The UV light excites the DNA SafeView (fluorophore) that is bound to the DNA