Question

Humans have one of four blood types: A, B, AB, or O. Explain what determines a person’s blood type. What antigens are on the blood cells in a person with each of these blood types? What antibodies are in the blood of a person with each of these blood types?

Answer 1

Human gene I (isohaemagglutinin) has three allelic forms: Iᴬ, Iᴮ, and i. Iᴬ produces type A antigens on the red blood cells. Iᴮ produces type B antigens. i which is a recessive allele does not produce any antigen.

• Human blood type is determined by antigens on the red blood cells and exists as four possible phenotypes: A, B, AB, & O.

• Blood group A (IᴬIᴬ or Iᴬi) has A antigens on the red blood cells with anti-B antibodies in the blood plasma.

• Blood group B (IᴮIᴮ or Iᴮi) has B antigens on the red blood cells with anti-A antibodies in the blood plasma.

• Blood group O (ii) has no antigens on the red blood cells but has both anti-A and anti-B antibodies in the blood plasma.

• Blood group AB (IᴬIᴮ) has both A and B antigens on the red blood cells but no antibodies in the blood plasma.