MGSLG. (2020). Module 1 Unit 4

Different blood groups and the genetics behind them

Blood grouping

Humans have different blood groups and this is a result of multiple alleles. The alleles namely IA, IB and i in different combinations result in four different blood groups. Learners are expected to solve genetic crosses regarding the different blood groups.

The phenotype will be the blood type and the genotype has to indicate the two different alleles present. Blood group O has two recessive alleles namely i.  Blood group A and B has co-dominant alleles.

The following table indicates the phenotype, genotype of each blood group:

Phenotype/Blood type

Genotype

 

A

 

IA IA

 

A

 

IA i

 

B

 

IB IB

 

B

 

IB i

 

AB

 

IA IB

O

i i























Co-dominance in humans:

  • Homozygous dominant = IA IA (blood group A)
  • Homozygous dominant = IB IB (blood group B)
  • Heterozygous = IA IB (blood group AB)
  • Homozygous recessive = ii (blood group O)







Last modified: Wednesday, 17 March 2021, 1:00 PM