Blood and Blood Evidence

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 BloodPLASMA (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

Composition of Blood

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 TypingABo

3 alleles within our populationA = Allele coding for type A surface proteinsB = Allele coding for type B surface proteinso = Allele coding for NO surface proteins

A & B alleles are codominanto 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 GroupsPhenotypes and Genotypes

Phenotypes

GENOTYPES???

AA or Ao BB or Bo AB ONLY oo ONLY

Sample Problems

#1If 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?#2A 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 TypingRh 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 GroupingRh+ = 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 #5Calculate the probability of person being Type 0 Blood and Rh- (O- Blood Type).

• Sample Problem #6Calculate the probability of a person having… AB / Rh+ / MM .