Genetic fingerprinting Flashcards
What is genetic fingerprinting
Diagnostic tool that is based on the fact that everyones DNA, except identical twins, is unique.
What are non coding DNA bases known as
VNTRs
Variable number tandem repeats
What is significant about VNTRs
For every individual the number and length of VNTRs is unique. If someone is closely related, the VNTRs will be similar.
What does gel electrophoresis do and how
Separates DNA fragments based upon their size.
DNA fragments are placed on agar gel with a voltage across it. The bigger the fragments, the more the resistance so the slower it moves.
5 stages of genetic fingerprinting
Extraction
Digestion
Seperation
Hybridisation
Development
Extraction stage
DNA is separated from the rest of the cell. Quantity can be increased with PCR
Digestion stage
DNA cut into fragments using restriction endocuclease.
Development stage
For X ray probes, x ray film is put over nylon membrane and film exposed to radiation. In fluorescent, positions can be located visually
Separation stage
Fragments are separated by size via gel electrophoresis under voltage. DNA fragments transferred to nylon membrane
Hydridisation stage
Radioactive or fluorescent probes used to bind with VNTRs under specific conditions
How are the results interpreted?
The more similar the lengths of distances of DNA between the samples, the more likely the 2 sets of DNA come from the same person.
Uses of genetic fingerprinting.
Genetic relationships
Forensic science
Plant and animal breeding
Medical diagnosis
