In simple Mendelian inheritance alleles display a simple dominant/recessive rela

Question

In simple Mendelian inheritance alleles display a simple dominant/recessive relationship. There are many exceptions to Mendelian laws of inheritance. Most genes have more than two allelic forms and do not exhibit simple Mendelian inheritance. The human ABO antigens are an example of a multiple allelic trait. There are three ABO blood group antigens, IA, IB and i. The i allele is recessive to both IA and IB. A person who is homozygous ii has type O blood and does not produce either the IA or IB antigens. A homozygous IAIA or heterozygous IAi individual has type A blood. Similarly, a homozygous IBIB or heterozygous IBi individual produces surface antigen B. A person who is IAIB has the blood type AB and expresses both surface antigens A and B as the IA and IB alleles are codominant to each other.

A child with blood type O is born to a mother with type A blood. What is the genotype of the mother?

Explanation / Answer

Ans) the baby will get O blood group only when the mother with blood group A with genotype IAIO. If the mother with IAIA genotype the baby must have the blood group A but not O blood group. So the baby has O blood group when the mother with IAIO genotype only.

Antibodies are the glycoproteins located in plasma, provide protection against the pathogens by eliminating them from the body and antigens are present the cell membrane. Based on the presence and absence of Antibodies in plasma & antigens on RBC membrane, ABO blood group system classifies the blood into four types. In 1900 the ABO system was first identified by the Karl Landsteiner and awarded with Nobel Prize in 1930.

A person with blood group A has A antigen on RBC and B antibodies in plasma

A person with blood group B has B antigen on RBC and A antibodies in plasma

A person with blood group AB has AB antigens on RBC and no antibodies in plasma

A person with blood group O has no antigens on RBC and   AB antibodies in plasma

In humans blood group system controlled by the single gene I and it has three alleles i.e. multiple alleles. These three alleles are responsible for different blood groups.

Blood group                                                   Genotype

A                                                                     IAIA / IAIO

B                                                                     IBIB / IBIO

AB                                                                  IAIB     

O                                                                     IOIO       

If mother IAIO genotype then the baby will have the O blood group

Mother                          father                                      (Baby) the possible blood groups of offspring

IAIO                             X         IAIO                               =          IAIA / IAIO / IOIO / IOIO

If mother IAIA genotype then the baby will not have the O blood group     

Mother                          father                                      (Baby) the possible blood groups of offspring

IAIA                             X         IAIO                               =          IAIA / IAIO / IAIA / IAIO

I am highly grateful to you if you rate this question

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.