Chapter 18 - Section 18.3 - Study Guide - Assess Your Learning Outcomes - Page 705: 1

A person's blood type is determined by the presence or absence of certain antigens on the surface of their red blood cells (RBCs). The two main systems that contribute to a person's blood type are the ABO blood group system and the Rh factor (Rhesus factor). 1. **ABO Blood Group System:** The ABO blood group system is based on the presence or absence of two antigens, A and B, on the surface of red blood cells. These antigens are determined by the inheritance of specific alleles from parents. There are four main blood types in the ABO system: - Type A: Has A antigens on the surface of RBCs. Genotype can be either AA or AO. - Type B: Has B antigens on the surface of RBCs. Genotype can be either BB or BO. - Type AB: Has both A and B antigens on the surface of RBCs. Genotype is AB. - Type O: Has neither A nor B antigens on the surface of RBCs. Genotype is OO. The presence of A and B antigens is controlled by a gene located on chromosome 9. The gene has three main alleles: A, B, and O. The A and B alleles are co-dominant, while the O allele is recessive. This means that if an individual has an A allele and a B allele, they will express both antigens (blood type AB). If an individual has an A allele and an O allele, they will express only the A antigen (blood type A), and if they have two O alleles, they will have blood type O. 2. **Rh Factor (Rhesus Factor):** The Rh factor, also known as the Rhesus factor, is another antigen that can be present on the surface of red blood cells. The presence or absence of the Rh factor is denoted by the + or - symbol, respectively. - Rh-positive (+): Has the Rh antigen on the surface of RBCs. - Rh-negative (-): Does not have the Rh antigen on the surface of RBCs. The Rh factor is determined by a different gene, the RhD gene, located on chromosome 1. The inheritance pattern is simpler than that of the ABO system. If an individual inherits at least one Rh+ allele (heterozygous or homozygous), they will express the Rh antigen. In summary, a person's blood type is determined by a combination of the ABO system and the Rh factor. The ABO system is influenced by the inheritance of alleles from both parents, while the Rh factor is determined by the presence or absence of the RhD antigen. These genetic factors interact to give rise to the various blood types observed in the population.

A person's blood type is determined by the presence or absence of certain antigens on the surface of their red blood cells (RBCs). The two main systems that contribute to a person's blood type are the ABO blood group system and the Rh factor (Rhesus factor). 1. **ABO Blood Group System:** The ABO blood group system is based on the presence or absence of two antigens, A and B, on the surface of red blood cells. These antigens are determined by the inheritance of specific alleles from parents. There are four main blood types in the ABO system: - Type A: Has A antigens on the surface of RBCs. Genotype can be either AA or AO. - Type B: Has B antigens on the surface of RBCs. Genotype can be either BB or BO. - Type AB: Has both A and B antigens on the surface of RBCs. Genotype is AB. - Type O: Has neither A nor B antigens on the surface of RBCs. Genotype is OO. The presence of A and B antigens is controlled by a gene located on chromosome 9. The gene has three main alleles: A, B, and O. The A and B alleles are co-dominant, while the O allele is recessive. This means that if an individual has an A allele and a B allele, they will express both antigens (blood type AB). If an individual has an A allele and an O allele, they will express only the A antigen (blood type A), and if they have two O alleles, they will have blood type O. 2. **Rh Factor (Rhesus Factor):** The Rh factor, also known as the Rhesus factor, is another antigen that can be present on the surface of red blood cells. The presence or absence of the Rh factor is denoted by the + or - symbol, respectively. - Rh-positive (+): Has the Rh antigen on the surface of RBCs. - Rh-negative (-): Does not have the Rh antigen on the surface of RBCs. The Rh factor is determined by a different gene, the RhD gene, located on chromosome 1. The inheritance pattern is simpler than that of the ABO system. If an individual inherits at least one Rh+ allele (heterozygous or homozygous), they will express the Rh antigen. In summary, a person's blood type is determined by a combination of the ABO system and the Rh factor. The ABO system is influenced by the inheritance of alleles from both parents, while the Rh factor is determined by the presence or absence of the RhD antigen. These genetic factors interact to give rise to the various blood types observed in the population.