21.5 Genetic fingerprinting Flashcards
what is genetic fingerprinting?
diagnostic tool used to identify family relations or in forensic science to identify people
what are the 5 steps of genetic fingerprinting
- Extraction
- Digestion
- Separation
- Hybridisation
- Development
what is extraction?
extracting DNA from sample
what is digestion?
restriction endonuclease cut DNA into fragments
what is separation?
separating fragments using gel electrophoresis and transfer from gel to nylon membrane
what is hybridisation?
adding DNA probes to label DNA fragments
what is development?
Nylon membrane with DNA fragments placed on X ray film or UV
Development of the film reveals dark bands where the probes are attached
what are VNTRs?
- non coding
- inherited from parents
- unique in all except twins
main points for gel electrophoresis
- DNA fragments placed on gel with voltage across
- DNA moves through gel
- Larger fragment = slower movement
- separate strands
- fragments labelled
- determine final position
- develop
what is gel electrophoresis used for?
separation of fragments of DNA in size order
what way is the DNA placed, what way does it travel?
- placed at the negative end of the gel
- DNA is negative, so travels to the anode (positive end)
How is the distance produced?
distance (depending on size) travelled over a fixed time
how do you separate the strands?
use alkali - apply to nylon membrane
how are the fragments labelled?
using DNA probes
how are the DNA probes identified?
- using X ray film for radioactive isotopes
- use UV for fluorescent markers
= exposes the film and maps the fragments
