Blood Types

Co-dominance When two or more alleles for a gene contribute to the phenotype

Blood type alleles IA = type A marker (antigen) IB = type B marker (antigen) IO or just i = No markers (antigen) Antigen – means marker on the surface of a cell **antigens are how your body can identify which cells belong to you and which are foreign**

Antigens vs. Antibodies Antigens (markers on your cells) are how your body recognizes which cells are yours and which cells are foreign. Antibodies are what your body produces to fight off any cell that is not “marked” as yours.

THINK – PAIR - SHARE If there are 3 co-dominant alleles, how many different blood types (phenotypes) are possible? 4 possible blood types A B AB O

Type A blood genotypes = IAIA or IAi Has only A antigens on the surface Has Anti-B antibodies A A A A A

Type B blood genotypes = IBi or IBIB Has only B antigens on the surface Has Anti-A antibodies B B B B B

Type AB blood genotype = IAIB Has A and B antigens on the surface B A No antibodies! A B B A A B

Type O blood genotype = IO IO or ii Has NO antigens on the surface Makes Anti-A and Anti-B antibodies

Fig. 14.21

Rh Blood Group Rh positive indicates presence of antigen D Rh negative indicates absence of Antigen D Rh antigens, like A and B antigens are inherited and present from birth Anti-D antibodies are not produced until after an individual is sensitized to antigen D

What blood can I receive? Blood type: Can receive from: Can give to: Type A A or O A or AB Type B B or O B or AB Type AB A, B, AB or O *UNIVERSAL RECIPIENT AB only Type O O only A, B and AB *UNIVERSAL DONOR

What happens if the wrong blood type is given?