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?

1,000,000

1,000,000,000

PCR cycles20 4030

Theorecticalyield

Actual yield“Plateau effect”

No.

of

DN

A c

opie

sHow much DNA

amplification has occurred?

How do scientists

analyse these PCR products?

Agarose Gel Electrophoresis

Separates DNA fragments according to

their size

Step 1 – Agarose is added to buffer and heated to 95ºC (to melt it). After cooling, it is poured into a pre-preparedcasting tray

Step 2 – a comb is inserted immediately to create wellsfor 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

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

Agarose gel

Loading DNA samples

Agarose gel

Loading DNA samples

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”

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Separating the DNA Fragments

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Separating the DNA Fragments

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Separating the DNA Fragments

Visualising DNA

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

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