Blood Types
3. Write down 3 questions & 3 facts you
know about blood.
Read pgs. 324 beginning with Multiple
Alleles Govern Blood Types and finish at
the end of 325
If possible answer any of your 3 questions
or add to your 3 facts if possible.
Blood Typing
All ABO blood types are determined by 2
proteins called antigens, the A antigen
and the B antigen.
 These proteins occur on the surface of
red blood cells.
 An individual’s blood may contain one,
both or neither of these antigens, forming
the 4 blood groups: A, B, AB and O.

Blood Type A have the A antigen on the
red blood cells.
 Blood group B have the B antigen.
 Blood group AB have both A and B
antigens.
 Blood group O have no antigens.


The A and B alleles are dominant to the O
allele.

The A and B alleles are co-dominant with
one another.
Blood Group
Genotype
A
AA or AO
B
BB or BO
AB
AB
O
OO

Antibodies are special immune cells that
destroy antigens that your body does not
recognize.
This results in agglutination, the
clumping of red blood cells = BAD.
 This is why blood types must match.

Blood
Types
Antigens Antibodi Can get
on the
es in the blood
RBCs
plasma
from
Can give
blood to
A
A
Anti-B
O, A
A, AB
B
B
Anti-A
O, B
B, AB
AB
A and B
None
A, B, AB, AB
O
O
None
Anti-A
Anti-B
O
O
Problem 1

A man has been taken to trial in a paternity suit
by a woman who claims he is the father of her
son. The man claims innocence. At the trial the
expert witness disclosed the blood types of all
three, as follows:
– The Woman: Type A
– The Man: Type B
– The Child: Type O
Could the man be the father of the child?
Problem 1



The woman could have the genotype AA or AO
The man could have the genotype BB or BO
If the woman possessed the genotype AO and the man
had BO, then the cross could look like this:
B
Yes, the man
could be the father.
However, any man
with type B, A or O
could be the father, so
this man cannot be indicted
on this evidence alone.

A
O
O
AB
AO
BO
OO
Problem 2

Mr. and Mrs. Jones have just come home with
their first child, but they are disturbed because
their friends say that the baby looks like
neither one of them. Have they come home
with the wrong baby?
Mrs. Jones A; Mr. Jones O; Baby Jones AB
Problem 2
Mrs. Jones could be AA or AO
 Mr. Jones can only be OO

O
A
A
AO
AO
O
AO
AO
O
O
AO
AO
OO
OO
A
O
Mr. Jones can NOT be the natural father!
 Mrs. Jones could be the mother

Problem 3

John and Barry are hiking when Barry falls
down a cliff and severs an artery. At the
hospital, John offers to donate his blood
for a direct transfusion for Barry. John has
type O blood, and Barry has type AB.
Strictly based on blood type, should the
hospital accept or refuse John’s offer?
Why?
Problem 3

Accept.
– John has Type O blood, he is a universal
donor – he can donate to any other type.
Problem 4

John and Barry are hiking again, and this
time John falls and gets hurt. Barry offers
to return to favor of a blood transfusion at
the hospital. Should the offer be accepted
or rejected? Why?
Problem 4

Rejected.
– Barry has Type AB Blood. Although he can
receive blood from any other type, he can
only donate to other people with Type AB.
– John has Type O Blood. Although he can
donate blood to any other type, he can only
receive blood from other people with Type O.
 Otherwise, his anti-A and anti-B antibodies will
attack the A and B anitgens in the blood, leading
to agglutination.

Biology2008_HumanGenetics.ppt