1. DNA Fingerprinting Simulation Step 1: Pour restriction enzymes into DNA

2. 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

3. Step 2: Pour agarose gel into tray on lab counter

4. 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

5. Step 3: Pour DNA into tray

6. What Happens? The DNA is added to depressions, or holes, in the agarose gel http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall- 2007/51DB7724-07DA-45ED-A3CE-7C06AA5C1963/0/mod1_2_agaro_gel.jpg http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall- 2007/381532A7-44EE-4E62-9F57- 83DEA4D0EFBA/0/mod1_2_photo.jpg

7. Step 4: Turn on switch to begin electrophoresis

8. 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.

9. http://ocw.mit.edu/NR/rdonlyres/Biological-Engineering/20-109Fall-2007/381532A7-44EE- 4E62-9F57-83DEA4D0EFBA/0/mod1_2_photo.jpg

10. Step 5: Place nylon membrane on top of the gel

11. 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)

12. Step 6: Add probes to nylon membrane

13. 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

14. Step 7: Place x-ray film on top of nylon membrane

15. 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

16. Step 8: Develop film by dragging it to the developer

17. What happens? The film is developed and shows the locations on the nylon membrane where the probes attached themselves to DNA fragments.

18. The results Carmela Honey Candy

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