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Blood Type Genetics
In traits with multiple alleles, each
individual can carry any two of the
several possible alleles.
Ex. BLOOD TYPE
The gene for blood type has 3 possible
alleles.
Blood Group Genes
• There is 1 gene for blood type
• There are 3 alleles for blood type:
A, B, & i (O).
• A&B are codominant
dominant to i (O).
and
both
The ABO blood system
Genotypes
Phenotypes (Blood types)
IA IA
IA IB
IA i
IB IB
IB i
ii
A
AB
A
B
B
O
Note:
• Blood types A and B have two possible genotypes –
homozygous and heterozygous.
• Blood types AB and O only have one genotype each.
© 2007 Paul Billiet ODWS
How blood types work….
How common are the 4
blood types?
4%
11%
45%
40%
http://www.lanecountyblood.org/images/other/bloodfacts.jpg
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
Practice Problems:
1. A mother is IA IB and a father is ii. Draw the
punnett square.
IA
IB
i
i
What is the probability their offspring will have A
type blood?
Can they have an offspring with O blood?
Practice Problems:
1. A mother is IA IB and a father is ii. Draw the
punnett square.
i
i
IA
IA i
IA i
IB
IB i
IB i
What is the probability their offspring will have A type
blood?
50%
Can they have an offspring with O blood? No
2. A mother is IAi and a father is IB IB Draw the
punnett square.
What is the probability their offspring will have B
type blood?
Can they have an offspring with O blood?
2. A mother is IAi and a father is IB IB Draw the
punnett square.
What is the probability their offspring will have B
type blood?
Can they have an offspring with O blood?
Rh Factors
• Scientists sometimes study Rhesus monkeys
to learn more about the human anatomy.
While studying Rhesus monkeys, a certain
blood protein was discovered. This protein is
also present in the blood of some people.
Other people, however, do not have the
protein.
• The presence of the protein, or lack of it, is
referred to as the Rh (for Rhesus) factor.
• If your blood does contain the protein, your
blood is said to be Rh positive (Rh+). If your
blood does not contain the protein, your blood
is said to be Rh negative (Rh-).
http://www.fi.edu/biosci/blood/rh.html
A+ AB+ BAB+ ABO+ O-