Question

Explain ABO  blood group system in human being with a suitable chart.

Answer 1

On the surface of plasma membrane of RBC’s, certain glycoprotein molecules called antigens are present. These antigens differ in different persons and give blood grouping properties to them.
i. ABO blood group system
ii. Rh-blood group system

1. ABO blood group system was discovered by Karl Landsteiner.
2. In the ABO system, blood groups are determined by the presence or absence of antigen A and antigen B.
3. Antigen: Blood groups are based on two antigens present on the membranes of RBCs, namely antigen A and antigen B. Person may have neither of them or one of them or both of them.
4. Antibody: It is γ-globulin protein present in blood plasma, so is called plasma factor. There are two types of antibodies a and b. A person may have neither of them, one of them, or both of them.
5. Antigen A and antibody a and antigen B and antibody b are incompatible with each other and cause self-clumping. On the basis of this, four blood groups are recognized.

Blood Group	Antigen	Antibody	Can give blood to	can receive blood from	Genotype
A	A	b	A, AB	A, O	`I^AI^A ` or `I^Ai`
B	B	a	B, Ab	B, O	`I^BI^B` or `I^Bi`
AB	A, B (both)	none	AB	All (Universal recipient)	`I^AI^B`
O	none	a, b (both)	All(universal Donor)	O	`ii`

A person with blood group O is called a universal donor as it has no antigen and can donate blood to any person. A person with blood group AB is called a universal recipient as it has no antibody in their plasma so can receive blood from any blood group.