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SBI 3U
Multiple Alleles
Multiple Alleles: Human Blood Groups
• In humans a single gene controls a person’s
ABO blood type
• This gene determines what type of an antigen
protein is attached to membrane of a red
blood cell
• Three alleles A,B and O
Multiple Alleles
•
Three blood type alleles: IA,
IB , i
•
The alleles for blood types A
and B are codominant
•
Blood type O is homozygous
recessive
BLOOD GROUPS
PHENOTYPE
GENOTYPE
BLOOD TYPES
• A human blood group or “type” is a group of red
blood cells that have the same antigen protein
markers on the cell surface
• There are four human blood groups:
• A, B, AB, O
Blood Type
% Amongst
Canadians
Can
Receive
From
Can Donate
To
A
42
A, O
A, AB
B
9
B, O
B, AB
AB
3
A, B, AB, O
AB
O
46
O
A, B, AB, O
BLOOD TYPES
• AB = Universal recipient (can receive from anyone)
• O = Universal donor (can donate to anyone)
Question: Multiple Alleles
1.
a.
b.
A woman with A type blood marries a
man with B type blood. They have a
child with type O blood.
The man says the child cannot be his.
Is he correct? Show your work to
prove you are right.
If this child belongs to this father, what
were the chances of having this child
with type O blood.
2. If a woman has AB blood, and a man
has type A blood, what are the possible
blood types of their offspring?