S3: HEREDITY E5: PEDIGREES Objective: Infer genotypes based on phenotypes in a pedigree GRAB YOUR NOTEBOOK and the green paper from the front I. HUMAN GENETICS AND PEDIGREES 2 I. HUMAN GENETICS AND PEDIGREES A. Human genetics follows the patterns seen in sexually reproducing organisms 3 I. HUMAN GENETICS AND PEDIGREES A. Human genetics follows the patterns seen in sexually reproducing organisms B. Females can carry sex-linked genetic disorders. 4 I. HUMAN GENETICS AND PEDIGREES A. Human genetics follows the patterns seen in sexually reproducing organisms B. Females can carry sex-linked genetic disorders. 1. Males (XY) express all of their sex-linked genes. 5 I. HUMAN GENETICS AND PEDIGREES A. Human genetics follows the patterns seen in sexually reproducing organisms B. Females can carry sex-linked genetic disorders. 1. Males (XY) express all of their sex-linked genes. 2. Males tend to show sex-linked disorders more than females 6 7 C. A Pedigree is a chart for tracing genes in a family. 8 C. A Pedigree is a chart for tracing genes in a family. 1.Phenotypes are used to infer genotypes 9 C. A Pedigree is a chart for tracing genes in a family. 1.Phenotypes are used to infer genotypes 2. Autosomal genes show different patterns than sex-linked genes. 10 How to read a pedigree: • □ = male How to read a pedigree: • □ = male • ○ = female How to read a pedigree: • □ = male • ○ = female • Horizontal lines between a male and female: marriage How to read a pedigree: • □ = male • ○ = female • Horizontal lines between a male and female: marriage • Horizontal lines above males and females: siblings How to read a pedigree: • □ = male • ○ = female • Horizontal lines between a male and female: marriage • Horizontal lines above males and females: siblings • Vertical lines: offspring How to read a pedigree: • □ = male • ○ = female • Horizontal lines between a male and female: marriage • Horizontal lines above males and females: siblings • Vertical lines: offspring • Colored in shapes: show the phenotype How to read a pedigree: • □ = male • ○ = female • Horizontal lines between a male and female: marriage • Horizontal lines above males and females: siblings • Vertical lines: offspring • Colored in shapes: show the phenotype • Half colored in shapes: carrier Example: Autosomal Pedigree • How many kids did the couple in generation I have? • How many of those kids got married? • How many boys/girls have the disease? • How does this pedigree show this disease is autosomal? • Is this a dominant or recessive disease? How do you know? • Write in the genotypes for each individual. 18 • How do autosomal dominant traits show up different on a pedigree than autosomal recessive traits? 19 Example: Sex Linked Pedigree • How many kids did the couple in generation I have? • How many boys/girls have the disease? • How does this pedigree show this disease is sex-linked? • Write in the genotypes for each individual • Is it possible for a female to have a sex linked disease? What would the parents’ genotypes have to be? 20 PEDIGREE WORKSHEET • GRAB A PEDIGREE WORKSHEET AND COMPLETE IT IN YOUR LAB NOTEBOOK • RETURN THE SHEET BEFORE THE BELL.