32.4 Using Biological Techniques

1. 32.4 Using Biological Techniques Blood group analysis

2. Blood group analysis Most common bodily fluid found at crime scenes - indicative of violence Forensic serology – examination and analysis of blood • Presumptive tests – is blood present? • Blood typing methods • DNA recovery

3. Blood is the body's transport system

4. What is “blood”?

5. Red Blood Cells (RBCs) • Red blood cells are filled with haemoglobin which lets the blood cells carry oxygen • aka erythrocytes

8. Activity 32.4A Find a labelled diagram of a red blood cell membrane. Describe the function of each structure: Lipid Carbohydrate Protein Glycoprotein Glycolipid

9. A A A A A A Antigens and antibodies • Antigen - A protein marker coating the surface of a red blood cell (RBC) that can stimulate an immune response – form an antibody. Can be A,B or O. • Antibody – proteins carried in the blood plasma that react with antigens on the RBCs.

10. ABO System In 1901, Austrian biologist Karl Landsteiner discovers ABO blood groups. • A antigens = blood type A • B antigens = blood type B • AB antigens = blood type AB • No antigens = blood type O

11. Rhesus System In 1940, Landsteiner and Alexander Wiener discovered another antigen in the blood of rhesus monkeys. • 85% of the human population have this antigen too (Rhesus Positive) • 15% don’t have it (Rhesus Negative)

12. A person may have these antigens on their red blood cells: This person will have these antibodies in their blood plasma: Their blood type is: A B A + B none A B AB O anti-B anti-A none anti-A + anti-B

13. groups are determined by the A and B markers on the surface of the red blood cell (antigens) Rhesus (Rh) is another marker (+/-) antibodies and antigens are called agglutinins and are found in the blood – if someone is given the wrong type of blood, clumps form - agglutination

14. If antibodies bind to antigens on the surface of red blood cells, the cells clump together.

16. donated blood is tested for blood group so it can be matched and used in blood transfusions

17. 32.4 Using Biological Techniques Skeletal physiology

18. Why study bones? • Bones often survive decay and provide the main evidence for the human form after death. • Forensic anthropology - the identification of skeletal, badly decomposed, or otherwise unidentified human remains. • Forensic anthropology can suggest the age, sex, ancestry (race), and stature (height) from the skeleton.

19. Inventory and Profile • The Forensic Anthropologist will make a complete inventory of the bones received. • Generalized, non-specific words such as "cranium" are not used; rather, the specific bone that is present is described. • If three bones of the skull are present, each will be identified – eg the left parietal, the occipital, and the right mastoid • If the skull is complete, that would be stated.

21. Race • Discriminate Function Analysis can identify racial ancestry from cranial measurements Black Caucasian “Mongol”

22. Gender • In order to determine sex, need to know the race. But in order to determine the race, we need to determine the sex. • In direct observation, a trained eye can separate male from female using parts of the skull and the pelvis.

23. Activity 32.4D • Forensic Scientists can use the pelvis to identify the sex of human remains. • Your job is to research the difference between the male and female pelvis. • Find diagrams and pictures of the pelvis for both sexes, label them and record differences in a table.

24. 32.4 Using Biological Techniques Hairs and Fibres!

25. Why study hair? • The scientific study of hair is called trichology • Chemical - use of illegal drugs, to screen for the presence of heavy metals in the body, and to test for nutritional deficiencies. • Biological - The root of the hair has cells that contain DNA, which can be used for DNA analyses. • Physical - Microscopic comparison of hair collected from different places can determine if the hairs are from the same person / animal.

26. Primary transfer - the presence of a specific person's hair can link a suspect or a victim to a crime scene. You lose ~100 head hairs per day. These usually end up on clothing, furniture, etc. • Secondary transfer – moving hair from one place to another. Common with animal hairs found on pet owners and in the environment of pet owners.

27. The Hair fibre • Cuticle – hard outer protective layer • Medulla – soft centre • Cortex – surrounds the medulla and comprise a bulk of the hair. Contains pigments.

28. Hair morphology There are 6 classifications of human hair: • head hair, • eyebrow and eyelash hair, • beard and moustache hair, • body hair, • pubic hair, • auxillary hair. • Biochemical studies show that there are no significant differences in chemical structure among the hair types.

29. Microscope analysis • Hair can be analysed for length, shape, size, colour, stiffness, curliness, pigmentation, and the appearance of the medulla. • Complications with the assignment of race involve analysis of hair from infants and from people of mixed race.