Facts, Factors and Inheritance BLOOD Facts, Factors and Inheritance

Blood Composition 55% of the blood consists of plasma 45% consists of formed elements 44% of the formed elements consist of erythrocytes 1% consists of leukocytes and platelets which is also called the buffy coat plasma buffy coat erythrocytes

plasma The liquid component of blood 90% of the plasma is made up of water 8% is made up of proteins 2% is made up of several ions

Blood cells Erythrocytes: red blood cells; function to transport oxygen Leukocytes: white blood cells; function to protect the body Platelets: cell fragments that function to clot the blood

Blood factors Blood cells, like other cells in the body, have proteins or factors located on their surfaces These factors can be antigens, substances that can cause the immune system to respond There are 3 important blood factors used to type a person’s blood: The ABO System The MNS System The Rh Factor

ABO System In the ABO system there are two different blood proteins: A and B The inheritance of these factors is based on codominance of the A and B proteins In codominance, both alleles (different forms of a gene) in the heterozygote express themselves fully There are 3 different blood alleles: The A and B genes are both dominant The o gene is recessive

Abo system (cont.) AA Ao BB Bo AB oo Based on the 3 genes there are 4 possible phenotypes: Type A blood Type B blood Type AB blood Type O blood There are 6 possible genotypes: Possible Genotypes AA Ao BB Bo AB oo Blood Types Type A Type B Type AB Type O

Abo system (cont.) A o B AB Bo o Ao oo The inheritance of the ABO system can be predicted using Punnett squares EX: A woman who is heterozygous for Type A blood has a child with a man who is heterozygous for Type B blood. What are the possible genotypes and phenotypes of their child? A o Genotypes: AB, Bo, Ao, oo B AB Bo Phenotypes: Type AB, Type B, Type A, Type O o Ao oo

Abo system (cont.) This system is important not only in forensics but in the medical field It is important for blood transfusions It is essential that the ABO blood types match to prevent the blood from clumping

ABO system (cont.) Type A Blood: Has A antigens and anti-B antibodies If this person receives type B or type AB blood, the blood will clump as the anti-B antibodies attack the B antigens Can receive type A and type O blood Makes up 40% of the population

ABO system (cont.) Type B Blood: Has B antigens and anti-A antibodies If this person receives type A or type AB blood, the blood will clump Can receive type B and type O blood Makes up 11% of the population

ABO system (cont.) Type AB Blood: Has A and B antigens and no ABO antibodies Because this person doesn’t have ABO antibodies, they can receive any type blood, making this person the universal recipient Makes up 4% of the population

ABO system (cont.) Type O Blood: Has no antigens and anti-A and anti-B antibodies Because this person doesn’t have antigens, they can donate to any type blood, making this person the universal donor Can only receive type O blood Makes up 45% of the population

Mns system Similar to the ABO System A person carries either the M protein, the N protein or the S protein on their blood cells M is found in 30% of the population N is found in 22% of the population S is found in 48% of the population

Rh Factor The Rh protein can be found on the surface of the blood cell Rh+: the person has the Rh antigen; it is found in 84% of the population Rh-: the person does not have the Rh antigen; makes up 16% of the population O+ 38 percent of population O- 7 percent of population A+ 34 percent of population A- 6 percent of population B+ 9 percent of population B- 2 percent of population AB+ 3 percent of population AB- 1 percent of population

Calculating probabilities Knowing the percentages of the population with the different blood factors can be used to determine the likelihood of a certain combination of blood factors By multiplying the ratios of the types, you can determine the probability of having a certain blood type

Calculating probabilities (cont.) EX: What is the probability of a person having blood type A and N and being Rh-? A N Rh- 40% x 22% x 16% = ? .40 x .22 x .16 = .01 1 out of every 100 people would have blood type A and N and be Rh-