Justice Watch 

                              "How DNA Works" 

                 [ Main ] [ Post New Thread ] [ Help ] [ Search ] 


                              Table of Contents 
                 ................................................................... 
      How DNA Works, Dunvegan, 23:43:00, 8/31/2001

                 ................................................................... 



   "How DNA Works"
   Posted by Dunvegan on 23:43:00 8/31/2001

        Another entry from the "How Stuff Works" site:

        http://www.howstuffworks.com/dna-evidence.htm

        Simple and gets you up to speed on the basics.

        An excerpt:

             Creating a DNA profile: The Basics

             The basic procedure used to isolate an individual's DNA fingerprint is called
             Restriction Fragment Length Polymorphism (RFLP) analysis. This is a
             complicated way of saying that investigators determine the number of VNTR
             repeats at a number of distinctive loci to come up with an individual's DNA
             profile.


             Here is the key to DNA evidence:

                  If you are looking at a particular person's DNA, and a particular VNTR
                  area in that person's DNA, there is going to be a certain number of
                  repeats in that area. What you do to make a DNA fingerprint is to
                  count the number of repeats for a specific person for a specific VNTR
                  area. For each person, there are 2 numbers of repeats in each VNTR
                  region (one from mom and one from dad), so you are getting both
                  counts. If you do this for a number of different VNTR regions, you can
                  build a profile for a person that is statistically unique. The resulting
                  DNA fingerprint can then be compared with the one left by the "perp"
                  at a crime scene to see if there might be a match.


             Here's how it works in general:



                1.Isolate the DNA.
                2.Cut the DNA up into shorter fragments containing known VNTR
                  areas.
                3.Sort the DNA fragments by size.
                4.Compare the DNA fragments in different samples.




                                                            [ ALERT ] [ EDIT ] 
                                     [ REPLY ] [ REPLY WITH QUOTE ] [ TOP ] [ MAIN ] 





   ARCHIVE
   REMOVE