Genetic Fingerprinting

VNTRs

Variable number tandem repeats

type of DNA which mutates the most

introns (non coding regions)

why VNTRs can be to identify people in genetic fingerprinting

probability of two individuals having the same VNTR's is very low

how DNA fragments are made for GF

using a PCR

uses of genetic fingerprinting

-Forensic science

-medical diagnosis

-Animal and plant breeding

when endonucleases are used in GF

to cut large strands of DNA into fragments so the DNA can be separated out

how DNA is separated

using gel electrophoresis

how gel electrophoresis separates DNA

-DNA has a negative charge

-smaller fragments move further than larger fragments

Southern Blotting

DNA fragments transferred from the gel to the nylon membrane

Hybridisation

Radioactive DNA probes added to label the fragments.

how genetic fingerprinting is developed from nylon sheet

x-ray film reveals dark bands where radioactive probes have attached

reason DNA shows up on x-ray

DNA probes are radioactive so those which have bound to the fragments show up as dark bands on the X-ray film