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KEY CONCEPT DNA fingerprints identify people at the molecular level. REVIEW from 9.1. Gel electrophoresis is used to separate DNA fragments by size. A DNA sample is cut with restriction enzymes. Electrical current pulls DNA fragments through a gel.
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KEY CONCEPT DNA fingerprints identify people at the molecular level.
REVIEW from 9.1 • Gel electrophoresis is used to separate DNA fragments by size. • A DNA sample is cut with restriction enzymes. • Electrical current pulls DNA fragments through a gel.
A DNA fingerprint is a type of restriction map. • DNA fingerprints are based on parts of an individual’s DNA that can be used for identification. • based on noncoding regions of DNA that have repeating DNA sequences • number of repeats differs between people
X X A DNA fingerprint is NOT actually a fingerprint!
(mother) (child 1) (child 2) (father) DNA fingerprinting is used for identification. • DNA fingerprinting depends on the probability of a match. • Many people have thesame number ofrepeats in a certainregion of DNA. • The probability that two people share identicalnumbers of repeats inseveral locations isvery small.
x x 1 1 1 1 500 90 120 5,400,000 = 1 chance in 5.4 million people to have the same DNA fingerprint = • Individual probabilities are multiplied to find the overall probability of two DNA fingerprints randomly matching. 1 in every 500 people has 3 copies in location A 1 in every 90 people has 6 copies in location B 1 in every 120 people has 10 copies in location c • Several regions of DNA are used to make DNA fingerprints.
DNA fingerprinting is used in several ways. • evidence in criminal cases • paternity tests • (Who da’ Daddy???) • immigration requests • studying biodiversity • tracking genetically modified crops
Who Ate the Cheese? • Get into pairs • Each pair needs a Bio book • Read the Royal Incident Report • The restriction enzyme used will always cut between CCGG • Create you DNA Fingerprint restriction map CC GG Objective: You will examine crime evidence and model the process of gel electrophoresis and DNA fingerprinting to identify the person who ate the Queen’s cheese.