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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.
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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 In a pedigree, a circle represents a female; a square represents a male.
Reading Pedigrees I 1 2 II 3 2 1 4 5 III 1 4 2 3 ? IV 2 3 5 1 4 Highlighted circles and squares represent individuals showing the trait being studied. Section 12.1 Summary – pages 309 - 314
Reading Pedigrees I 1 Circles and squares that are not highlighted designate individuals that do not show the trait. 2 II 2 3 4 5 1 III 1 4 2 3 ? IV 3 5 2 4 1 Section 12.1 Summary – pages 309 - 314
Reading Pedigrees I A horizontal line connecting a circle and a square indicates that the individuals are parents, and a vertical line connects parents with their offspring. 1 2 II 4 2 3 1 5 III 1 4 2 3 ? IV 2 3 5 1 4 Section 12.1 Summary – pages 309 - 314
Reading Pedigrees A half-shaded circle or square represents a carrier, a heterozygous individual.
Reading Pedigrees Each horizontal row of circles and squares in a pedigree designates a generation, with the most recent generation shown at the bottom. I 1 2 II 3 1 2 4 5 III 1 2 4 3 ? IV 3 5 1 2 4
Reading Pedigrees The generations are identified in sequence by Roman numerals, and each individual is given an Arabic number. I 1 2 II 3 1 2 4 5 III 1 2 4 3 ? IV 3 5 1 2 4
Queen Victoria, Prince Albert and their 9 Children Alice Alfred Victoria Helena Edward Arthur Louise Leopold Beatrice
Hemophelia Genes XHXH = Female, normal XHY = Male, normal XHXh = Female, carrier XhY = Male, hemophiliac XhXh = Female, 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?