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DNA Fingerprinting

How does one create a DNA fingerprint?

What is DNA?
What is DNA Fingerprinting?
Types of DNA Fingerprinting
How does one create a DNA fingerprint?
The Uses of DNA Fingerprinting
Problems with DNA Fingerprinting
Gel Electrophoresis

The Steps to DNA Fingerprinting

The first step is to get the DNA from the specimen.  The sample of DNA can be obtained from skin, hair, nails, saliva, or blood.  Once the DNA is taken enzymes are used to cut it.  The cuts are then made in specific spots.  The enzymes are designed to cut in specific spots according to their genetic design.  The scientist has to be careful in which enzyme they use because each one cuts at specific spots.  Some restriction enzymes cut leaving blunt ends and some leave sticky ends.  The sticky ends are preferred because they are easier to work with because they attach to other pieces of DNA easily.  The blunt ends are more difficult to use because their ends do not match with other ends of other DNA.  A sticky end could look like this:          5’ AGAAGAGAGAGAG

                                                     TTTTCTTCTCTCTCTCTCTTT   3’

A blunt end could look like: 5’TTTTTTT

                                                  AAAAAAA 3’                                         

The DNA is then sorted by gel electrophoresis.  The following step is to transfer the piece of DNA to a nylon sheet and then it is soaked.  This hour long process is called capillary action.  After the transfer is complete the fragments are treated with ultra violet light which crosses links the DNA to the membrane.  The next step is probing.  The DNA is the annealed using a probe.  The last thing to do is visualize the final product using an autoradiograph.  





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