2. Gel Diffusion is when antibodies and antigens diffuse or move toward one another on a plate coated with a gel medium made from a natural polymer called agar. Helps determine what species the blood comes from: mostly used to determine human blood.

3. Extracted blood stain and human antiserum are placed in separated holes opposite each other on the gel. If blood is human, a line of precipitation forms where the antigens and antibodies meet.

4. Electrophoresis method –When an electrical potential is applied to the gel. There are also different tests for different substances such as drugs and saliva. –Different drugs include acetaminophen, chlorpheniramine, theophylline, ibuprofen, and indomethacin. –It is determined by the Fickian transport which is the study of the drug’s concentration in the gel. –Saliva test uses amylase to determine the amylase levels of vaginal, seminal and other body fluids. (Amylase is an enzyme produces the breakdown of starch to sugars.)

5. Electrophoresis method Drug diffusion Saliva diffusion

6. Advantages –severely tampered serum samples can be tested with high hopes. –simple, rapid, and costs less. –easily adopted by diagnostic laboratories Disadvantages –Semi quantitative – Moderate sensitivity –Can not be read easily –Takes 24 hours to perform

7. Carla Johnson went missing on September 14th, 2012. After weeks of thorough searching, police found a trail of blood that led to a large puddle of blood in front of a bear's den. Unaware of whether or not the blood was hers, forensic analysts performed gel diffusion on the sample of blood to determine what species it came from. The results showed that the blood came from a deer, and the search for Carla continued on.

8. North Shore Animal Hospital was known for its exceptional boarding services offered to people who went on long vacations and needed somewhere for their pets to stay. On 4th of July weekend, a grisly murder happened overnight. All the animals had disappeared along with 2 security guards. There was no trace left behind except for large amounts of blood. After countless gel diffusion tests were done, it was determined that the blood was from humans and a guinea pig. It seems that the culprit took the rest of the animals elsewhere.

9. 1.What is the purpose of gel diffusion? 2.Name the types of gel diffusion. 3.What is added in the electrophoresis method? 4.Name one disadvantage and one advantage of gel diffusion. 5.What is created in the center of gel diffusion? 6.What type of gel is used for gel diffusion?

10. Bell, Suzanne, and Robert R C. Shale. "Saliva." Encyclopedia of Forensic Science. New York, NY: Facts on File, 2004. 315-16. Print. Department of Chemical Engineering, Massachusetts Institute of Technology. "Hindered Diffusion in Agarose Gels: Test of Effective Medium Model." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 03 Apr. 2013.. School of Pharmacy, University of Missouri-Kansas Cit. "Diffusion and Concentration Profiles of Drugs in Gels." National Center for Biotechnology Information. U.S. National Library of Medicine, Nov. 1993. Web.. Senne, Dennis A. "Agar Gel Immunodiffusion (AGID) Test Principles and Techniques." National Veterinary Services Laboratories, n.d. Web.. Smith, P. C., and W. C. Stewart. "Agar-gel Immunodiffusion Assay for Pseudorabies Virus Antibody." U.S. National Library of Medicine. National Center for Biotechnology Information., 1978. Web..