Blood Type Inheritance and the
Punnett Square
Blood Type Inheritance
 Type O blood =
oo (recessive)
 Type B blood = BB (homozygous)
or
Bo (heterozygous)
 Type A blood = AA (homozygous)
or
Ao (heterozygous)
 Type AB blood = AB
Terms to be familiar with
 Homozygous = same letters (alleles)
 Heterozygous = different letters (alleles)
 Genotype = letters (inherit 1 from each parent)
 Phenotype = physical appearance of trait (actual
blood type)
 Dominant = shows up; covers up recessive trait
 Recessive = trait that can be masked
Punnett Square
Punnett Square
One parent’s genotype goes here
The
other
parent
goes
here
Punnett Square
One parent’s genotype goes here
The
other
parent
goes
here
Possible Offspring
Genotypes Go Here
Possible Offspring
Genotypes Go Here
Possible Offspring Genotypes Possible Offspring Genotypes
Go Here
Go Here
Punnett Square
One parent’s genotype goes here
The
other
parent
goes
here
Possible Offspring
Genotypes Go Here
(25% chance)
Possible Offspring
Genotypes Go Here
(25% chance)
Possible Offspring Genotypes Possible Offspring Genotypes
Go Here
Go Here
(25% chance)
(25% chance)
Example
Jack and Jill get married and have
a child. Jack is heterozygous for
the blood Type A and Jill has type
AB blood. What is the chance that
they will have a baby with type B
blood?
Punnett Square
Punnett Square
drop and drag to fill in the squares
A
o
A
B
AA
Ao
AB
Bo
the child will type A blood, 25% the child will
have type AB blood, and a 25% the child will
have B blood.
A
A
B
o
AA
Ao
AB
Bo
Example
Jack and Jill get married and have a
child. Jack is heterozygous for the
blood Type A and Jill has type AB
blood. What is the chance that they
will have a baby with type B blood?
Based on the results on the previous
slide, there is a 25% chance a child of
Jack and Jill’s will have type B blood.
Example 2
Bonnie and Clyde are having a baby and they
want to know if there is a chance that they
can have a child with Type O blood. Bonnie
is homozygous for type A blood and Clyde
has type O blood. What did you find out?
Punnett Square
Punnett Square
drop and drag to fill in the squares
o
o
A
A
Ao
Ao
Ao
Ao
They will not have a child with Type O
blood. There children will only have
type A blood (100% chance).
o
o
A
A
Ao
Ao
Ao
Ao