DNA Fingerprints

As introduced earlier, PCR concludes the isolation and amplification of DNA. To complete the DNA fingerprinting process, a restriction enzyme is used to cut the DNA into fragments at a certain sequence. Even though it is cut at a certain place, everybody that doesn't have an identical twin will have different DNA fingerprints because the DNA makeup is different so the lengths will vary. The little fragments that are formed are restriction fragment length polymorphisms, also known as RFLPs. RFLP analysis can be done to identify a change in genetic sequence that occurred when a restriction enzyme cut the DNA. Everybody also has genetic sequences known as variable number tandem repeats, also known as VNTRs. The varying amount of VNTRs lead to the different-lengthed RFLPs. (Sources: DNA Fingerprinting, RFLP Analysis, How DNA Fingerprinting Works, and DNA Fingerprinting (RFLP Analysis))

Creating a DNA Fingerprint!

Pour restriction enzymes into DNA. The restriction enzymes will cut the DNA at different locations; the location depends on the code inside the DNA and enzyme.
Pour agarose gel into a tray. The agarose gel has a thick, gelataneous texture and will allow smaller pieces of the DNA to pass through easily while trapping the larger pieces.
Pour the DNA into the tray. The fragmented DNA will sink into a hole into the agarose gel.
Push the "start" button on the tray to begin electrophoresis. Electrophoresis will move the DNA molecules with an electric force. Since DNA has a slightly negative charge, it will move towards the positive end of the tray. However, bigger pieces will move slower due to the agarose gel.
Place a nylon membrane on top of the agarose gel. Since the agarose gel is too filmsy to work with, the DNA is transferred onto the nylon membrane when the liquid from the gel traveled up towards the absorbent membrane.
Add probes to the tray. Probes are fragments of DNA that have been radioactively labeled. Based on the probe, it will attach to the DNA at a certain location.
Place X-ray film on top of the nylon membrane. The radioactive probes will expose certain locations on the X-ray film.
Develop the film by putting it into the developer. The film will display where the probes attached to the DNA pieces.

(Source: Create a DNA Fingerprint)

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Still Don't Understand?

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