Download How Often Does my Blood Type Occur

How Often Does my Blood Type Occur?
Section ___ Name _________________
Introduction:
There are four blood types: A, B, AB, O. Here are the percentages of the types in the
US population.
Type O = 44%
Type A = 37%
Type B = 13%
Type AB = 6%
We know how to find out what type of blood each person has and we think that the
different blood types are related to germs.
When you get germs or bacteria in your body, your body starts fighting them. Some of
your white blood cells act like amoebas and eat and digest the bacteria. Other cells
produce chemicals called ANTIBODIES, which help destroy the bacteria. The bacteria
have certain chemicals on the cells, called ANTIGENS. These antigens cause your body
to make antibodies. Each antigen has a matched antibody.
It is the same way with blood. For each blood antigen, A and B, there is a special
antibody: antibody A and antibody B. Type a has antigen A, Type B has antigen B. If
you have Type AB blood, you have antigen A and antigen B on your red blood cells.
The antibodies cause the cells to “clump” together. This “clumping” is called
agglutination.
Knowing about the different blood types has improved blood transfusion as well as
allowing better matches with transplanted organs and tissues which require even more
detailed research.
Fill in the antibodies in the chart below:
BLOOD TYPE
ANTIGENS
Type A
A
Type B
B
Type AB
AB
Type O
None
ANTIBODIES
Explain why someone with Type A blood cannot be given Type B or type AB blood:
________________________________________________________________
________________________________________________________________
Explain why someone with Type O blood is thought to be a universal donor:
________________________________________________________________
________________________________________________________________
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The chart is based on the hypothesis that there are 3 genes for blood type rather than
the usual 2. It is possible for any person to have 2 of the possible 3 genes. There is a
gene for Type A blood, a gene for Type B blood, and a gene for Type O blood. The O
gene is recessive to the other 2 genes (A and B). A person with both an A gene and a
B gene will have Type AB blood.
Complete the chart by circling who the other parent can be, and cannot be.
Draw Punnet squares if you need help figuring out possible parentage.
Possible Blood Type of a Baby and His Parents
If the baby is blood type…
And one parent is…
O
Then the other parent
can be
but cannot be
O
A, B, AB, O
A, B, AB, O
O
A
A, B, AB, O
A, B, AB, O
O
B
A, B, AB, O
A, B, AB, O
O
AB
A, B, AB, O
A, B, AB, O
A
O
A, B, AB, O
A, B, AB, O
A
A
A, B, AB, O
A, B, AB, O
A
B
A, B, AB, O
A, B, AB, O
A
AB
A, B, AB, O
A, B, AB, O
B
O
A, B, AB, O
A, B, AB, O
B
A
A, B, AB, O
A, B, AB, O
B
B
A, B, AB, O
A, B, AB, O
B
AB
A, B, AB, O
A, B, AB, O
AB
O
A, B, AB, O
A, B, AB, O
AB
A
A, B, AB, O
A, B, AB, O
AB
B
A, B, AB, O
A, B, AB, O
AB
AB
A, B, AB, O
A, B, AB, O
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How do genes control the Rh factor?
Although several genes are involved in controlling Rh, we will simplify the matter by
representing it as Rh+ as dominant and Rh- as recessive.
Therefore,
Someone:
Someone:
Someone:
Rh+ Rh+  is Rh positive (+)
Rh+ Rh-  is Rh positive (+)
Rh- Rh-  is Rh negative (-)
The chart below shows pairs of Rh genes that parents could have. For each
combination of parent genes, some pairs of offspring genes are possible. Other pairs of
offspring genes are impossible. Look at the first line. It shoes that ++ is the only pair
of gene a child of these parents could have.
Now, you complete the rest of the chart. Write in the space provided, the
pairs of genes that the children of each set of parent could have.
Notice that in some cases more than one pair of genes is possible.
Gene Pair of
First Parent
Gene Pair of
Second Parent
Possible Gene Pairs of Children
+ +
+ +
+ +
+ +
+ -
+ +
-
+ -
+ -
+ -
-
-
-
-
-
-
-
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