Blood and Blood Evidence SEROLOGY • Serology- the study of blood – 1901- Karl Landsteiner discovers ABo blood groups. • 29 years later was awarded Nobel Prize for this feat. – 1937- Rh factor was identified – Up until early 1990’s many other blood factors were being studied in an attempt to individualize blood evidence • class vs individual evidence Composition of Blood Composition of Blood PLASMA (55%)- fluid portion of blood * similar to salt water -mainly water -dissolved salts, nutrients, proteins, antibodies, hormones ect… SUSPENDED MATERIALS (45%)- “free floating” materials/cells *Red blood cells = ERYTHROCYTES -carry oxygen *White blood cells = LEUKOCYTES -fight disease and foreign invaders *platelets = THROMBOCYTES -blood clotting and repair of damaged blood vessels KEY TERM • Antigens- substances, usually proteins, that can be found on the surface of our cells. – Creates ABo blood group – Creates Rh+/Rh- blood group – Many other blood groups have been identified as well Blood Typing ABo 3 alleles within our population A = Allele coding for type A surface proteins B = Allele coding for type B surface proteins o = Allele coding for NO surface proteins A & B alleles are codominant o is recessive to both the A and B allele Each person inherits 1 allele from each parent to determine their ABo blood type ABo Blood Groups Phenotypes and Genotypes Phenotypes AA or Ao BB or Bo AB ONLY GENOTYPES??? oo ONLY Sample Problems #1 If a woman who is heterozygous with type A blood (Ao) marries a man with type O blood, what is the probability that their children will have type A blood? B blood? AB blood? O blood? #2 A woman who is homozygous with type B blood (BB) has a child out of wedlock that has type O blood. She files a paternity suit against a man with type O blood. Is the lawsuit valid? Blood Typing Rh Factor • Rh factor is another type of surface protein which may be produced on the surface of our cells. • Rh+ (producing Rh protein) is dominant over being Rh- (not producing Rh protein) • R = allele for production of Rh protein (Rh+) • r = allele for NO Rh protein (Rh-) • Each person inherits 1 allele from each parent GENOTYPES AND PHENOTYPES RR = Rh+ blood Rr = Rh+ blood rr = Rh- blood Sample Problems #3 • A man who is Rh- marries a woman who is heterozygous with Rh+ blood. What is the probability that their children will be Rh+? Rh-? #4 • A woman who is homozygous with Rh+ blood marries a man who is heterozygous with Rh+ blood. Is it possible for them to have a child who is Rh-? Using Blood Typing as Class Evidence • Identifies the presence or absence of particular proteins embedded in the cell • Quicker and less expensive than DNA profiling • Produces class evidence but can still link a suspect to a crime scene or exclude a suspect US Population and Blood Groups • US Population & ABo Blood Grouping Type A Blood – 42% Type AB Blood – 3% Type B Blood – 12% Type O Blood – 43% • US Population and Rh Blood Grouping Rh+ = 85% Rh- = 15% • US Population and MN Blood Grouping (another blood group not mentioned yet) MM – 30% MN – 48% NN – 22% Sample Problems • Sample Problem #5 Calculate the probability of person being Type 0 Blood and Rh- (O- Blood Type). • Sample Problem #6 Calculate the probability of a person having… AB / Rh+ / MM .