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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
Describe stage 1 of genetic fingerprinting
DNA is extracted from the sample and amplified using PCR
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
Describe stage 3 of genetic fingerprinting
The fragments are separated via gel electrophoresis
Describe stage 4 of genetic fingerprinting
The gel is washed in alkali to make the DNA single stranded to allow the probe to bind
Describe stage 5 of genetic fingerprinting
Radioactive probes, containing sequences complementary to the repetitive sequence of interest are added and allowed to hybridise
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
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
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
How might plant and animal breeders use genetic fingerprinting?
To establish how closely two organisms are related
This is useful for avoiding inbreeding
AQA BIOL5 Genetic fingerprinting