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Crime Scene Investigation
Who Ate The Cheese?
Oh no! Someone ate the Queen’s prize Limburger cheese!
Saliva samples were taken from the teeth marks left on the cheese
How can we determine who ate the cheese?
DNA Fingerprinting
A process which uses fragments of DNA to identify the unique genetic makeup of an individual. 1. PCR
2. Restriction Enzymes
3. Electrophoresis
PCR
Polymerase Chain Reaction– Replicates DNA sample– Produces millions of copies in 2 hours
Restriction Enzymes
Molecules that cut DNA segments into smaller pieces by breaking bonds
Cuts DNA into fragments of different lengths
Gel Electrophoresis
GEL ELECTROPHORESIS– DNA molecules have a negative charge. – The molecules migrate toward the positive
pole. – The larger the molecule, the more difficult it
is to make its way through the gel, so the shorter segments move farther than longer ones.
DGGE
Denaturing gradient gel electrophoresis DNA melts! Temperature of melting point
determined by G/C content Can separate DNA by melting point =
different genes
Who ate the cheese?
Today you are going to solve a crime using the techniques you just learned!
Crime Scene Photo
