Many Genes have more than two alleles in the population

Most genes can be found in populations in more than two versions known as multiple alleles. Two possible alleles exist in the wider population. Three alleles of a simple gene is involved by ABO blood group phenotype. Human blood types consist of O, A, B, or AB. A person's red blood cells may have carbohydrate A (Type A Blood), carbohydrate B (Type B), Both (Type AB), or neither (Type O). Safe blood transfusions must have a compatible match as it is very critical. Various combinations of these different alleles in the four blood groups, symbolized as 1a (for the enzyme that adds carbohydrate A to red blood cells), 1b (for B), and i (for neither A & B), both 1a & 1b alleles are dominant to the i allele. 1a1a & 1ai people have Type A blood, and 1b1b and 1bi people have Type B. ii, recessive homo-zygotes have Type O blood because the blood have neither A or B, both alleles expressed in hetero-zygotes individuals (1a1b), who have type AB blood are called co dominant.






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