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DNA Fingerprinting Simulation. Step 1: Pour restriction enzymes into DNA. What happens. The restriction enzymes act like scissors that cut the DNA into smaller fragments Because each person has a unique DNA sequence, his or her DNA is cut in a unique pattern
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DNA Fingerprinting Simulation • Step 1: Pour restriction enzymes into DNA
What happens • The restriction enzymes act like scissors that cut the DNA into smaller fragments • Because each person has a unique DNA sequence, his or her DNA is cut in a unique pattern • The lengths of the fragments will vary from person to person
What happens • Agarose gel has a web-like molecular structure similar to that of Jell-O • The agarose gel separates the DNA fragments based on size because larger fragments have a harder time moving through the “web” and move more slowly than smaller fragments
What Happens? • The DNA is added to depressions, or holes, in the agarose gel http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall-2007/381532A7-44EE-4E62-9F57-83DEA4D0EFBA/0/mod1_2_photo.jpg http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall-2007/51DB7724-07DA-45ED-A3CE-7C06AA5C1963/0/mod1_2_agaro_gel.jpg
What happens? • The electric current causes the DNA molecules to begin moving • DNA fragments have a slight negative charge, so they move toward the positive end of the gel/tray. • By the end of electrophoresis the fragments will be separated according to their lengths.
http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall-2007/381532A7-44EE-4E62-9F57-83DEA4D0EFBA/0/mod1_2_photo.jpghttp://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall-2007/381532A7-44EE-4E62-9F57-83DEA4D0EFBA/0/mod1_2_photo.jpg
What happens? • The agarose gel is very thin and difficult to move around, so a nylon membrane is placed on top of it • The nylon membrane “blots” up the DNA (kind of like a paper towel)
What happens? • The radioactive probes attach themselves to DNA fragments that have stuck to the nylon membrane • Any excess (non-stuck) probes are washed away
What happens? • The radioactivity from the probes exposes the x-ray film in any places where the probes have attached • You can visualize the locations where the probes have stuck to the nylon membrane
What happens? • The film is developed and shows the locations on the nylon membrane where the probes attached themselves to DNA fragments.
The results Carmela Honey Candy
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