1

Required large amounts of samples

DNA Fingerprinting

Traces are relatively small

Amplify DNA

Polymerase Chain

Reaction (PCR)

Thermal cycler

2

Each cycle takes

about 5 minutes

PCR

Typically run 25 to 35

cycles each time

3

Allows a specific region of DNA

to be repeatedly duplicated

PCR results

25 to 35 cycles

1 million copies

Very small trace

Converted 1 million times

4

Can analyse very small amounts

PCR results

Saliva from cigarette ends or back of a stamp

Low copy number

9 cells

Barely visible blood stains

36 cells