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The Case of the Crown Jewels: DNA in Forensics. Image from: http://climategate.tv/?tag=criminal-investigation. DNA: Individually Unique Molecules. Base pair sequences are unique for each person DNA contains the genes that determine individual characteristics
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The Case of the Crown Jewels: DNA in Forensics Image from: http://climategate.tv/?tag=criminal-investigation
DNA: Individually Unique Molecules • Base pair sequences are unique for each person • DNA contains the genes that determine individual characteristics • Remember: DNA bases are paired and is easily extracted from most cells Image from: http://www.britannica.com/EBchecked/topic-art/528804/40216/DNA-molecule
Restriction Enzymes • Highly specific substances that cut DNA into precise restriction fragments • Each cuts DNA at a different sequence of nucleotides Miller, K.R., & Levine, J.S. (2010). Biology. Upper Saddle River, NJ: Pearson Education, Inc. Image from: http://www.mcdb.lsa.umich.edu/labs/ttzfira/research.php
Gel Electrophoresis • Utilizes negative charge of DNA • Uses electricity to cause movement of restriction fragments • Porous agar gel necessary for fragment movement Miller, K.R., & Levine, J.S. (2010). Biology. Upper Saddle River, NJ: Pearson Education, Inc. Image from : https://sites.google.com/a/luther.edu/genetics/students/elise-desroches/gel-electrophoresis
Gel Electrophoresis • DNA samples loaded • Electricity is applied • Fragments move from (-) to (+) end • Smaller DNA fragments move farther and faster • Gives a pattern of bands • Specific stains make the bands visible Image from: http://isbibbio.wikispaces.com/Gel+Eletrophoresis Miller, K.R., & Levine, J.S. (2010). Biology. Upper Saddle River, NJ: Pearson Education, Inc.
The Complete Process Image from : http://cg.scs.carleton.ca/~morin/teaching/compbio/electro.html
DNA in Forensics: The Case of the Crown Jewels DNA fingerprinting : Individual DNA contains unique restriction fragments, therefore people can be identified by the combination of the different lengths of DNA. Separation by gel electrophoresis is used to match DNA from crime scenes to suspects or to identify deceased individuals.