DNA Finger-Printing Web Lab
The following are screenshots of the web lab, in order. The objective of this lab was to "solve the crime" by finding the criminal through finding their fingerprints through using the DNA in a gel via electrophoresis.
THE PROCEDURE: (from the web-lab) site
- Step 1: Pour restriction enzymes into DNA
The restriction enzymes cut the long DNA molecules at different locations. Where they cut depends on the code within the DNA molecule and the restriction enzymes. The lengths of these DNA fragment vary from person to person because the code for every person's DNA is different.
Step 2: Pour Agarose gel into tray on lab counter
Agarose gel is a thick, porous, jello-like substance. It will act as a molecular strainer, allowing smaller pieces of DNA to move through more easily than larger pieces.
Step 3: Pour DNA into tray
Pouring the DNA into a hole made in the agarose gel, the fragments now lies there.
Step 4: Push "Power" button on tray to begin electrophoresis
Turning on the power begins electrophoresis which is the process of moving molecules with an electric current. The DNA fragments have a slightly negative charge, so they move towards the positive side of the tray. However the gel acts as a strainer: smaller DNA fragments travel through the gel more easily than longer ones. When electrophoresis is complete, the fragments are distributed in the gel according to their lengths.
Step 5: Place nylon membrane on top of the gel
Because the gel is so difficult to work with, the DNA is transferred to a nylon membrane. It looks like a sheet of paper. The DNA was sucked up into the membrane as liquid traveled up from the gel toward an absorbent material that was placed over the membrane.
Step 6: Add probes to the nylon membrane in the tray
The probes are pieces of DNA that have been radioactively labeled. The probes attach themselves to the DNA fragments on the nylon membrane. They attach only where their code encountered a certain sequence of code among the various fragments. Excess probes- the ones that didn't attach to a DNA fragment- is washed away.
Step 7: Place X-ray film on top of nylon membrane in tray
The radioactivity of the probes, which are now present at only a few locations on the nylon membrane exposes corresponding areas on the X-ray film.
Step 8: Develop film by dragging it to the developer
The film displays the locations on the nylon membrane where the probes attach themselves to the DNA fragments.
Step 9: Choose the culprit
Here, we drag the DNA we had gathered and see which suspect has the same exact DNA.( IT WAS HONEY!)
DNA FINGERPRINTING "WET" LAB
THE WEB-LAB corresponded with a wet lab, or real lab, that we performed with a partner using a similar procedure (minus the membranes, probes, and developing) and the following materials:
- A Micro Pipette (to pipette 12 mL of each "culprit's" DNA into separate wells along with distilled water in the gel)
- An agarose Gel slab with 6 wells for DNA
- The gel platform, with runs current through the gel, starting electrophoresis
- The Eppendorf, a small tube that holds both the distilled water and DNA
- The Eppendorf Tray (Self Explanatory)
- The Eppendorf Centrifuge for combining DNA and distilled water