a Use T+t instead of a+b in the square of sum's model.
B
b Let each square in the genetic table represent 25 %
A
a (T+t)^2=T^2+2Tt+t^2
B
bBoth Dominant: 25 % One Dominant: 50 % Both Recessive: 25 %
Practice makes perfect
a Recall how the square of a sum can be modeled.
(a+b)^2 = a^2+2ab+b^2
In the case of this genetic table, we see that each parent has one T and one t gene. We can replace the general model with a=T and b=t.
(T+t)^2=T^2+2Tt+t^2
That mirrors what we see in the table, one TT, two Tt, and one tt.
b To predict the percent of offspring that will have each of the types of genes, let's assume each square in the genetic table has an equal chance of happening.
T
t
T
TT
Tt
t
Tt
tt
The TT gene combination shows up 1 out of 4 times, so it has a 25 % possibility of occurring. The Tt gene combination shows up 2 out of 4 times, so has a 50 % possibility of occurring. The tt gene combination also shows up 1 out of 4 times and has a 25 % possibility of occurring.
