Blood Evidence Chapter 10

Serology Study of bodily fluids Saliva Semen Urine Blood

2 tests for blood at crime scene 1. Presumptive Test Tests if blood is present 2. Precipitin Test Tests if blood is human or animal

Luminol Use on areas that may have been cleaned, reacts with hemoglobin in blood

CSI: Miami http://www.youtube.com/watch?v=iNl-I4DUSyI

Blood is made up of 4 parts Plasma: Fluid part of the blood Red blood cells: carry oxygen, determine blood type White blood cells: fight infection, can contain DNA Platelets: for blood clotting

Class vs. Individual Blood type is CLASS evidence DNA is INDIVIDUAL evidence Blood spatter is circumstantial evidence

Blood facts Human body has 5 liters of blood 1 billion red blood cells in a drop of blood For every 600 red blood cells there are 40 platelets and 1 white blood cell

How common are the 4 blood types? What are blood types? There are 3 alleles or genes for blood type: A, B, & O. Since we have 2 genes, there are 6 possible combinations. http://www.lanecountyblood.org/images/other/bloodfacts.jpg 45% 40% 11% 4% How common are the 4 blood types? http://learn.genetics.utah.edu/units/basics/blood/types.cfm

Rh Factors A+ A- B+ B- AB+ AB- O+ O- While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein. The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor. If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-). Rh+ = 85% Rh- = 15% A+ A- B+ B- AB+ AB- O+ O- http://www.fi.edu/biosci/blood/rh.html

Genotypes & Phenotypes: Remember biology freshman year? AA or AO Type A BB or BO Type B AB Type AB OO Type O

More vocabulary Antigen: proteins on the red blood cell, give the cell its type Antibody: immune proteins that are in your blood that attack foreign substances Agglutination: when blood type testing, this is when there is clumping (if antigen and antibody match)

14. Use the results shown to determine the blood type for each sample. Blood Typing 14. Use the results shown to determine the blood type for each sample. - = No Clumps + = Clump A B Rh Blood Type: ___ To determine a person’s blood type, we add three different serums to blood samples and see if clumps form. Clumps = Positive (+) No Clumps = Negative (-) What would the blood type be for this sample? #13

- = absent + = present Blood Typing Rh Blood Type: ___ A B Rh Blood Type: ___ Blood Typing Use the results shown to determine the blood type for each sample. A B Rh Blood Type: ___ A B Rh Blood Type: ___ A B Rh Blood Type: ___ - = absent + = present

How can blood be used as EVIDENCE? Blood samples – Can be analyzed to determine BLOOD TYPE and DNA, which can be matched to possible suspects. Blood droplets – Can be analyzed to give clues to the location of a WOUND, MOVEMENT of a victim, and type of INJURY. Blood spatter – Can be analyzed to determine PATTERNS that give investigators clues to how a crime might have happened.

Assignment Using the notes you just took: Create a 15 question quiz Collect Randomly hand out to complete Each quiz should have 2 names: the creator and the quiz taker Due at end of class

http://www.nobelprize.org/educational/medicine/bloodtypinggame/