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Heredity and ABO Blood group system HTML5


This animation represents the characteristics of the A, B, O and AB blood groups.

Also it addresses the inheritance of blood groups by using a pedigree chart.

Red blood cells (called erythrocytes) are the principle consituents of blood. They contain the hemoglobin that transports CO2 and O2 in an organism.

The four blood groups A, B, O and AB get their names from the characteristic antigens (or agglutinations) that are found at the surface of the red blood cells. They exist in two types: A and B antigens.

In addition, in the blood plasma, specific antibodies circulate called agglutinates. They can be of two types: anti-A antibodies and anti-B antibodies.

  • In an individual of group A blood, the red blood cells present, at their surface, the type A antigens only. The plasma only contains anti-B antibodies
  • In an individual of group B blood, the red blood cells present, at their surface, the type B antigens only. The plasma only contains anti-A antibodies.
  • An individual of group AB blood, simultaneously possesses both the A and B antigen on the red blood cells, but no anti-A or anti-B antibodies in the plasma.
  • An individual of group O blood, does not possess A or B antigens on the red blood cells but the plasma contains both anti-A and anti-B antibodies.

In the tab 'Pedigree chart', click on the symbol for an individual to modify his/her phenotype. The descendants are not modified, therefore the pedigree chart may be false.

Learning goals

  • To define the following terms: gene, allele, homozygous, heterozygous, recessive, dominant, codominant, phenotype, genotype.
  • To analyze the genealogy tree.
  • To address the notion of blood group A-B-O.

Learn more

Before a blood transfusion, it is important to assure that the blood group of the donor and recipient are compatible. Therefore, if the blood of the donor has complementary antibodies to the…

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