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Genetic fingerprinting

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Title: Genetic fingerprinting Author: Keith Last modified by: Tommy Botha Created Date: 4/21/2004 8:13:41 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Genetic fingerprinting


1
Genetic fingerprinting
  • Each DNA profile is unique!

2
Genetic fingerprinting
  • Regions of chromosomes that code for proteins are
    called introns.
  • Other regions that are non-coding are called
    extrons.

3
Genetic fingerprinting
  • Extrons contain blocks of repeated nucleotides
    called short tandem repeats (STRs)
  • It is the number of times that these STRs are
    repeated that produces the variations in
    individuals.

4
Genetic fingerprinting
5
How it is done part 1
  • DNA is extracted from sample.
  • Cut into millions of small fragments
  • Using restriction endonucleases
  • Aimed at STRs

6
How it is done part 2
  • DNA fragments are separated by electrophoresis
  • (Fragments are exposed to electric current in a
    trough of gel)
  • Different fragments move at different rates
    through the gel.

7
How it is done part 2
  • The smaller the fragment the faster it moves.
  • DNA is separated into bands according to size of
    the fragments.

8
How it is done part 3
  • The pattern of fragments are transferred to a
    nylon membrane by a process called Southern
    blotting.

9
How it is done part 4
  • Radioactive probes are used to attach to specific
    parts of the fragments.
  • Any probes not bound are washed off.
  • The membrane is dried

10
How it is done - part 5
  • The nylon sheet is placed under X-ray film.
  • The radioactive probes on the DNA fragments
    expose the film.
  • This produces visible pattern of light and dark
    bands which is unique to each individual.
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