Genetic fingerprinting

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  1. How can the genome of an individual be said to be unique?
    • Each person's genome contains many repetitive, non coding base sequences that are found in introns and between genes 
    • Each individual has a unique number and length of these sequences (other than MZ twins) 
    • The more closely related people are, the more similar their sequences
  2. Describe stage 1 of genetic fingerprinting
    DNA is extracted from the sample and amplified using PCR
  3. Describe stage 2 of genetic fingerprinting
    • DNA is cut into fragments using restriction endonucleases 
    • The endonucleases are chosen to have recognition sequences that are not part of the repeating sequence of interest
  4. Describe stage 3 of genetic fingerprinting
    The fragments are separated via gel electrophoresis
  5. Describe stage 4 of genetic fingerprinting
    The gel is washed in alkali to make the DNA single stranded to allow the probe to bind
  6. Describe stage 5 of genetic fingerprinting
    Radioactive probes, containing sequences complementary to the repetitive sequence of interest are added and allowed to hybridise
  7. Describe stage 6 of genetic fingerprinting
    X ray film is laid across the gel and the positions of the fragments are revealed as dark bands
  8. How might forensic scientists use genetic fingerprinting?
    • The patterns of bands allows DNA from different sources to be compared 
    • DNA from a crime scene can be compared with that of a suspect
  9. How might genetic fingerprinting be used for medical diagnosis?
    • Some repetitive non coding base sequences are linked to genetic diseases such as huntingtons 
    • The more of these repeats the person possesses, the more likely they are to suffer from the disease 
    • The longer the sequence of repeats, the larger the fragment which will show up as a band on the gel
  10. How might plant and animal breeders use genetic fingerprinting?
    • To establish how closely two organisms are related 
    • This is useful for avoiding inbreeding
Card Set
Genetic fingerprinting
AQA BIOL5 Genetic fingerprinting
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