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Set CornellGenetics Notes on pg. 7.4 up Human and Pedigrees 81 7.4 Human Genetics and Pedigrees 2.1 Atoms, Ions, and Molecules •Topic: 7.4 Human Genetics and Pedigrees KEY CONCEPT A combination of methods •Essential Questions: is used to study human 1. NO EQ genetics. 7.4 Human Genetics and Pedigrees KEY CONCEPT A combination of methods is used to study human genetics. 7.4 Human Genetics and Pedigrees • The basic principles of genetics are the same in all sexually reproducing organisms. – Inheritance of many human traits is complex – Single-gene traits are important in understanding human genetics. Ex: widow’s peak Widow’s peak 7.4 Human Genetics and Pedigrees A pedigree is a chart for tracing genes in a family. • Phenotypes are used to infer genotypes Please copy on Pg. 80 Pedigree Key: Boxes = males Circles = females Shaded = they show the trait White = does not show trait Half shaded = carrier (Carrier= Only for recessive disorders) 7.4 Human Genetics and Pedigrees 1. 2. 3. 4. How many females are in this family? Pg. 80 How many carriers? How many children were in generation two? How many offspring in generation three are affected by the trait? Generation 1 Generation 2 Generation 3 Generation 4 7.4 Human Genetics and Pedigrees 1. How many females are in this family? 11 2. How many carriers? 7 3. How many children were in generation two? 5 4. How many offspring in generation three are affected by the trait? 2 Generation 1 Generation 2 Generation 3 Generation 4 7.4 Human Genetics and Pedigrees Autosomal Dominant Trait- Many family members will show the trait in the pedigree Widow’s peak No Widow’s peak On 81, please create thisand pedigree and answer the following 7.4pg. Human Genetics Pedigrees questions: Jamie and Joe married in 1912. Joe was homozygous dominant for a Widow’s Peak, while Jamie did not have a Widow’s Peak. They had two children: A son named Kyle and a daughter named Marie. Kyle married a woman who had no Widow’s Peak. Marie never married. Kyle and his wife had three children: Two boys and a girl. • Do Kyle and Marie have Widow’s Peaks? • What percent of Kyle’s children can we expect to have Widow’s Peaks? • What percent of Kyle’s children can we expect to have NO Widow’s Peaks? 7.4 Human Genetics and Pedigrees Joe Jamie LL x ll • 100% Ll ll LL ll Kyle Marie Ll Ll Ll x ll ? ? ? • 50% Ll and 50% ll 1. Yes, Kyle and Marie have Widow’s Peaks 2. 50% should have Widow’s Peaks 3. 50% should have NO Widow’s Peaks 7.4 Human Genetics and Pedigrees Autosomal Recessive Disorders will show up if carriers mate, may skip a few generations before reappearing. Only a few, will show the trait/disorder On pg. 81, Fill in the genotypes of this incomplete pedigree. Shade if necessary. aa 7.4 Human Genetics and Pedigrees On pg. 81, Fill in the genotypes of this incomplete pedigree. Shade if necessary. aa 7.4 Human Genetics and Pedigrees Albinism is an autosomal recessive disorder. Fill in the genotypes. Shade if necessary Aa aa Prob. ? Aa aa Aa Aa Aa or AA Aa ? aa aa Aa ? AA or Aa 7.4 Human Genetics and Pedigrees Pg. 80 Mary and Joe were married in 1950. Both Mary and Joe were carriers for a fatal recessive disorder called Cystic Fibrosis. They had three children: A son named Pete who was a carrier, a son named Charles who was not a carrier and did not have the disease, and a girl named Isabel who died from Cystic Fibrosis. Pete married a woman who was homozygous dominant. Pete and his wife are worried about having a child with Cystic Fibrosis. Should they worry? What are the chances of any of their children having Cystic Fibrosis? Carriers? 7.4 Human Genetics and Pedigrees FF ? ? Joe Mary Ff Ff Pete Charles Isabel Ff FF ff ? FF x Ff • O%- No chance of any of their children having the disorder • 50% will be carriers 7.4 Human Genetics and Pedigrees Females can carry sex-linked genetic disorders. • Males (XY) express all of their sex linked genes. • Expression of the disorder depends on which parent carries the allele and the sex of the child. Y X 7.4 Human Genetics and Pedigrees • Sex-linked traits: More males will show their sex-linked traits because they do not have another X to mask the disorder Ex: Color blindness males females 7.4 Human Genetics and Pedigrees XMXM= Normal XMXm= carrier XmXm= CB XMY= Normal XmY= CB X-linked Color Blindness- Recessive XmY XmY XMXm On pg. 80, Fill in the genotypes of this incomplete pedigree. Shade if necessary. XMXm XMXm XMXm XMY ? XmY XmY XMXM or XMXm 7.4 Human Genetics and Pedigrees • A karyotype is a picture of all chromosomes in a cell. XY 7.4 Human Genetics and Pedigrees • Karyotypes can show changes in chromosomes. – deletion of part of a chromosome or loss of a chromosome – large changes in chromosomes – extra chromosomes or duplication of part of a chromosome 7.4 Human Genetics and Pedigrees • In down syndrome a person has an extra copy of chromosome 21. • In Klinefelter’s syndrome a male has an extra X (XXY).