“Bloody Punnett Squares!!!”
Background Information: There are two factors that are typically
reported for blood type: ABO type and Rh factor. For example,
blood type A
+
or AB
-
. Each factor is determined by a separate gene.
Blood type genotypes and phenotypes are listed in the table to the
right. For example, the blood phenotype A has two possible
genotypes: I
A
I
A
and I
A
i. The blood phenotype Rh negative has one
genotype Rh
-
Rh
-
. Often, the two factors are reported together such
as blood phenotype AB
-
. When the two traits are reported together,
the genotypes get a bit more complicated. For example, the genotype
for AB
-
is I
A
I
B
Rh
-
Rh
-
. Whereas the phenotype A
+
has several
possible genotypes: I
A
i Rh
+
Rh
-
or I
A
i Rh
+
Rh
+
or I
A
I
A
Rh
+
Rh
-
or
I
A
I
A
Rh
+
Rh
+
. Use the information in the table to the right to help you
solve the ‘bloody’ problems.
** Notice: According to the symbols used in the table to the
right, the allele for blood type ‘O’ is recessive to the alleles for
both ‘A’ and ‘B’ blood types.
1. Tracy has a blood type of AB and her husband, Trevor, also has a blood type of AB. What are the
possible blood types of their children? Make a Punnett Square and summarize the phenotypic
percentages!!!
2. Michelle was curious about her mother’s blood type. Michelle knew that her own blood type was O,
her father’s blood type was A, and her two sisters and one brother both also had type A blood. How
could Michelle have type O when everyone else around her seems to have type A blood? Michelle is
really frustrated. Please help her out by making a possible Punnett square showing how this could
happen.
3. John’s father has type AB blood and his mother has type O blood. What are the possible blood types
that John could have?
Genotypes Phenotypes
I
A
I
A
Type A
I
A
i Type A
I
B
I
B
Type B
I
B
i Type B
I
A
I
B
Type AB
ii Type O
Rh
+
Rh
+
+
Rh
+
Rh
-
+
Rh
-
Rh
-
-
Name:
Period:
