A pedigree is a chart of a person's ancestors that is used to analyze genetic inheritance of certain traits -
especially diseases. The symbols used for a pedigree are:
O female, unaffected
O male, unaffected
female, affected
male, affected
Siblings are placed in birth order from left to right and are labeled with numbers.
Each generation is labeled with a Roman numeral.
Example: we would name an individual 11-3 if he/she was in the second generation and the 3
child bom
110
D
O 5 Dė i
IIIo oIo od
4
5
6
7
8
9
1
2
3
4
6
7
8
Try to identify the genotypes of the following individuals using the pedigree above.
(homozygous dominant, homozygous recessive, heterozygous)
• III-3: nomozilabus dominant
• 1-1:
• 11-1:_bomozygous
. 11-4:
1. Is this trait dominant or recessive? Explain your answer.
2. How can you know for sure that individuals II-3 and 11-4 are heterozygous?
3. Brown eyes are a dominant eye-color allele and blue eyes are recessive. A brown-eyed woman whose father
had blue eyes and whose mother had brown eyes marries a brown-eyed man whose parents are also brown-
eyed. They have a son who is blue-eyed. Please draw a pedigree showing all four grandparents, the two
parents, and the son indicate which individuals you are certain of their genotype and where there are more
than one possibilities.