Blood Types
Objective: Determine how blood types are
inherited and how co-dominance applies to
the ABO system
Genetics of
Blood
•Your blood type is established before you are
born, by specific genes inherited from your
parents.
•These two genes - one gene from your mother
and one from your father - determine your
blood type.
Who Has What Type?
TYPES
DISTRIBUTION
RATIOS
O+
1 person in 3
38.4%
O-
1 person in 15
7.7%
A+
1 person in 3
32.3%
A-
1 person in 16
6.5%
B+
1 person in 12
9.4%
B-
1 person in 67
1.7%
AB +
1 person in 29
3.2%
AB -
1 person in 167
0.7%
source: http://www.bloodbook.com/type-facts.html
Application to Medical Field
CAN RECEIVE
O*
* O + B - B + A - A + AB - AB
Blood Types
AB+
AB A+
X
X
X
AB+
B-
X
X
X
O+
O-
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Genotypes & Phenotypes
•There are 4 different types of blood:
A, B, AB & O.
•Blood types (phenotypes) are determined by
the following allele or gene combination
(genotype):
Give the genotype(s) for each blood type.
AB
AO Type AB = ____
AA ____
Type A = ____
BO Type O = ____
OO
BB ____
Type B = ____
Dominant &
Recessive
• O is recessive
• A is dominant
• B is dominant
• What happens if A +
B?
Co-dominance
B
Since A & B are both
dominant it is co-dominant
AB
A
A new blood type results…AB
Example:
Dad has Type B blood type
(phenotype) because he has a B
gene (blue) and an O gene
(yellow) genotype.
B
Mom has Type
A blood
because she
has an A gene
(red) and an O
gene (yellow)
O
A
A
B
O
B O
A O
O O
Example:
A
Dad has Type B blood type
(phenotype) because he has a B
gene (blue) and an O gene
(yellow) genotype.
B
O
A B
A O
?
Mom has Type
A blood
because she
has an A gene
(red) and an O
gene (yellow)
O
B O
Type B phenotype
Type A phenotype
O O
Type O phenotype
Exercise
1:
Dad has Type A blood (phenotype)
because he has a A gene (red)
and an O gene (yellow)
A
O
Mom has Type O
blood (phenotype)
because she has an
O gene (yellow)
and an O gene
(yellow) genotype.
O
O
Answer
Key 1:
Dad has Type A blood (phenotype)
because he has a A gene (red)
and an O gene (yellow)
A
O
A O
Type A phenotype
Mom has Type O
blood (phenotype)
because she has an
O gene (yellow)
and an O gene
(yellow) genotype.
O
A O
Type A phenotype
O
O O
Type O phenotype
O O
Type O phenotype
Exercise
2:
Dad has Type A blood (phenotype)
because he has a A gene (red)
and an A gene (red) genotype
A
A
Mom has Type AB
blood (phenotype)
because she has an
A gene (red) and an
B gene (blue)
genotype .
B
A
Answer
Key 2:
Dad has Type A blood (phenotype)
because he has an A gene (red)
and an A gene (red) genotype
A
A
A
Mom has Type AB
blood (phenotype)
because she has an
A gene (red) and an
B gene (blue)
genotype .
A
A
A
A
Type A phenotype Type A phenotype
B
AB
A B
Type AB phenotype Type AB phenotype
Exercise 3:
Mom has Type B blood
(phenotype) because
she has an B gene
(blue) and an O gene
(yellow) genotype
Dad has Type B blood
(phenotype) because he
has a B gene (blue) and
an B gene (blue) genotype
Answer Key 3:
B
Dad has Type B blood
(phenotype) because he
has a B gene (blue) and
an B gene (blue) genotype
B
B
B B
BB
Type B phenotype
Mom has Type B blood
(phenotype) because
she has an B gene
(blue) and an O gene
(yellow) genotype
O
BO
Type B phenotype
Type B phenotype
BO
Type B phenotype
Exercise 4:
Mom has Type A
blood
(phenotype)
because she has
an A gene (red)
and an O gene
(yellow)
Dad has Type AB blood
(phenotype) because he
has an A gene (red) and a
B gene (blue) genotype
Answer Key 4:
Dad has Type AB blood
(phenotype) because he
has an A gene (red) and a
B gene (blue) genotype
A
Mom has
Type A blood
(phenotype)
because she
has an A
gene (red)
and an O
gene (yellow)
A
A A
Type A phenotype
O
B
AB
Type AB phenotype
A O
BO
Type A phenotype
Type B phenotype
Bonus
Exercise:
Mom has Type A
blood
(phenotype)
because she has
an A gene (red)
and an O gene
(yellow)
genotype.
Dad has Type B blood
(phenotype) because he
has a B gene (blue) and
an O gene (yellow)
genotype
Bonus
Answer Key:
Dad has Type B blood
(phenotype) because he
has a B gene (blue) and
an O gene (yellow)
genotype
B
Mom has Type A
blood
(phenotype)
because she has
an A gene (red)
and an O gene
(yellow)
genotype.
A
O
A B
Type AB phenotype
B O
Type B phenotype
O
A O
Type A phenotype
O O
Type O phenotype
Optional Extension
• Ask your parents if
they know their
blood type.
• Ask your parents if
they know your
blood type.