BLOOD TYPE Blood Typing All ABO blood types

BLOOD TYPE

Blood Typing • All ABO blood types are determined by 2 proteins called antigens, the A antigen and the B antigen. • These proteins occur on the surface of red blood cells. • An individual’s blood may contain one, both or neither of these antigens, forming the 4 blood groups: A, B, AB and O.

• Individuals with blood group A have the A antigen on the red blood cells. • Individuals with blood group B have the B antigen. • Individuals with blood group AB have both A and B antigens. • Individuals with blood group O have no antigens.

• Antibodies are special immune cells that destroy antigens that your body does not recognize. • This results in agglutination, the clumping of red blood cells.

• The A and B alleles are dominant to the O allele. • The A and B alleles are co-dominant with one another.

The illustration below shows that Type O blood is the universal donor (blood can be given to anyone and type B is the universal recipient (anyone blood type can receive this blood).

Problem 1 • A man has been taken to trial in a paternity suit by a woman who claims he is the father of her son. The man claims innocence. At the trial the expert witness disclosed the blood types of all three, as follows: – The Woman: Type A – The Man: Type B – The Child: Type O Could the man be the father of the child?

Problem 1 • • The woman could have the genotype IA IA or IA i The man could have the genotype or IBIB or IB i If the woman possessed the genotype IA i and the man had IB i, then the cross could look like this: • Yes, the man could be the father. However, any man with type B, A or O could be the father, so this man cannot be indicted on this evidence alone. IB A I I I i IB i i IA i ii

Problem 2 • Mr. and Mrs. Jones have just come home with their first child, but they are disturbed because their friends say that the baby looks like neither one of them. Have they come home with the wrong baby? Mrs. Jones A; Mr. Jones O; Baby Jones AB

Problem 2 • Mrs. Jones could be IA IA or IA i • Mr. Jones can only be i i i IA IA IA i i i IA IA i ii i IA i • Mr. Jones can NOT be the natural father! • Mrs. Jones could be the mother

Problem 3 • John and Barry are hiking when Barry falls down a cliff and severs an artery. At the hospital, John offers to donate his blood for a direct transfusion for Barry. John has type O blood, and Barry has type AB. Strictly based on blood type, should the hospital accept or refuse John’s offer? Why?

Problem 3 • Accept. – John has Type O blood, he is a universal donor – he can donate to any other type.

Problem 4 • John and Barry are hiking again, and this time John falls and gets hurt. Barry offers to return to favor of a blood transfusion at the hospital. Should the offer be accepted or rejected? Why?

Problem 4 • Rejected. – Barry has Type AB Blood. Although he can receive blood from any other type, he can only donate to other people with Type AB. – John has Type O Blood. Although he can donate blood to any other type, he can only receive blood from other people with Type O. • Otherwise, his anti-A and anti-B antibodies will attack the A and B anitgens in the blood, leading to agglutination.

• Biology 2008_Human. Genetics. ppt