Figure 7.3b. Steps in RFLP genotyping. The next step is to purify the DNA from the person who will be genotyped and then place the DNA into a mixture containing a large number of molecules of a specific restriction enzyme. The restirction enzyme will recognize a certain nucleotide sequence and cut the DNA at the sequence. In the present example, the restriction enzyme recognizes the seqeunce GATTC and cuts the DNA between the G and the first A in the sequence. The figure below shows how the Allele 1 responds to the restriction enzyme. It has the GAATC sequence at the beginning and at the end of the gene of interest, so the cut by the restriction enzyme will result in one long DNA sequence. (For simplicity, think of the DNA as being single stranded. Also ignore the beginning and the ending parts of the depicted allele--they will not bind with the probe anyway.)
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