How is the polymerase chain reaction useful in DNA fingerprinting?

[Ashley]

Also describe how gene therapy is being used into treat cystic fibrosis.

[m37786]

The primary method of assessing similarities is by use of DNA fingerprinting or DNA restriction analysis. This process makes use of special proteins called restriction enzymes and sections of the chromosome called tandem repeats. A region of the chromosome that contains multiple copies of a core DNA sequence that are arranged in a repeating fashion. Repeats act as fillers or spacers between coded sections of DNA
All humans have the same type of repeats but there is tremendous variation in the number of repeats that each of us has.

Restriction enzymes cut DNA but only at a certain combination of A, G, T, and C.
Different restriction enzymes cut DNA at different places—each has a unique sequence it recognizes.
The restriction enzyme EcoRI cuts DNA at the sequence GAATTC and will cut only at that sequence.

RFLPs are different fragment lengths of base pairs that result from cutting a DNA molecule with a restriction enzyme
It is the length differences associated with DNA strands or RFLPs that allow one to distinguish one person from another.