pedigrees
DESCRIPTION
Pedigrees. A tool used to track the inheritance of traits through a family. Pedigree Symbols. Symbols used by Geneticists. Female. Male. I. 1. 2. II. 2. 1. 3. 4. 5. III. 1. 4. 2. 3. ?. IV. 5. 3. 4. 2. 1. Reading Pedigrees. - PowerPoint PPT PresentationTRANSCRIPT
PedigreesPedigreesA tool used to track the inheritance
of traits through a family.
Symbols used by Geneticists
Pedigree SymbolsPedigree Symbols
Male Female
Does not show Trait
Shows Trait
Carrier (heterozygote)
Died from the trait
Reading PedigreesReading Pedigrees
In a pedigree, a circle represents a female; a square represents a male.
Female Male
?
I
II
III
IV
1 2
1
1
1
32
2
2
4
3
3
5
4
4 5
Highlighted circles and squares represent individuals showing the trait being studied.
?
I
II
III
IV
1 2
1
1
1
32
2
2
4
3
3
5
4
4 5
Reading PedigreesReading Pedigrees
Reading PedigreesReading Pedigrees
?
I
II
III
IV
1 2
1
1
1
32
2
2
4
3
3
5
4
4 5
Circles and squares that are not highlighted designate individuals that do not show the trait.
1 2
1
1
1
32
2
2
4
3
3
5
4
4 5
?
I
II
III
IV
A horizontal line connecting a circle and a square indicates that the individuals are parents, and a vertical line connects parents with their offspring.
Reading PedigreesReading Pedigrees
A half-shaded circle or square represents a carrier, a heterozygous individual.
Reading PedigreesReading Pedigrees
Reading PedigreesReading Pedigrees
Each horizontal row of circles and squares in a pedigree designates a generation, with the most recent generation shown at the bottom.
1 2
1
1
1
32
2
2
4
3
3
5
4
4 5
?
I
II
III
IV
Reading PedigreesReading Pedigrees
1 2
1
1
1
32
2
2
4
3
3
5
4
4 5
?
The generations are identified in sequence by Roman numerals, and each individual is given an Arabic number.
I
II
III
IV
Queen Victoria, Prince Albert and their 9 Children
Victoria
Edward
AliceAlfred
Helena
LouiseArthurLeopold
Beatrice
Hemophelia Genes
XHXH = Female, normal
XHXh = Female, carrier
XhXh = Female, hemophiliac
XHY = Male, normal
XhY = Male, hemophiliac
Show the cross of…• A woman who is a carrier marries a normal man.
• What is the probability that their children will have the disease? What sex will a child in the family with hemophilia be?