Biology 3A – Pedigree Genetics
Name:
Please write neatly – if I cannot read it, the question will be marked incorrect
1. Draw an invented pedigree where two normal parents without Duchenne’s muscular dystrophy (MD - a sex-linked
recessively inherited trait) have four children. The eldest of the children is a normal female (Wilma) without MD.
Barney, the second born a son has MD and died at a young age. This led the family to see a genetic counselor.
Their next two children, a daughter (Betty) and a son (Fred) are not afflicted.
Wilma marries a man with no MD. They have two sons and two daughters. The oldest son does not have MD and
has a normal daughter. Wilma’s second son has MD and dies when he’s five. Both of Wilma’s daughters are
normal. Wilma’s oldest daughter marries and has a normal son.
The youngest daughter Betty has three boys. The oldest does not have MD; however, the younger two sons both die
th
before their 10 birthday from MD. Betty’s only surviving son has two children, a son and a daughter. Both do not
have MD.
Construct a pedigree analysis for this family and give the possible genotypes for each member. (15 points)
Note: You need to first determine whether this is a dominantly or recessively inherited trait so that you draw the
pedigree symbols correctly. Please define which is female & male. Again this is sex-linked.
The two parents:
Wilma, Barney, Betty and Fred:
Wilma and Betty’s kids:
Wilma and Betty’s grandkids: