1. Gel electrophoresis Separating molecules by size and charge

2. Gel electrophoresis Image credit: biotechnologyonline.gov.au/biotechnologyonline.gov.au/

3. Electrophoresis of DNA  In electrophoresis an electric current is set up across a watery gel – agarose  Negatively charged molecules move to the positive terminal and positively charged molecules move to the negative terminal  Each nucleotide on the DNA molecule carries a negative charge  Therefore, DNA molecules only move from the negative cathode to the positive anode © 2010 Paul Billiet ODWSODWS

4. Electrophoresis of DNA  Negative charge increases with size, big DNA molecules move more quickly  However, bigger molecules move more slowly through the gel  The result is a steady and fine separation of DNA molecules by size  Molecules which differ by only one nucleotide in their length can be separated © 2010 Paul Billiet ODWSODWS

5. Electrophoresis of DNA Buffer solution Agarose Gel CATHODE - + ANODE Wells for the mixture DNA fragments separating by size Marker molecule indicates the front © 2010 Paul Billiet ODWSODWS

6. Gel electrophoresis Image credit: biotechnologyonline.gov.au/biotechnologyonline.gov.au/