7.4 Human Genetics and Pedigrees Set up Cornell Notes on pg. 81 Topic: 7.4 Human Genetics and Pedigrees Essential Questions: 1. NO EQ 7.4 Human Genetics and Pedigrees 2.1 Atoms, Ions, and Molecules KEY CONCEPT A combination of methods is used to study human genetics.

KEY CONCEPT A combination of methods is used to study human genetics.

Inheritance of many human traits is complex 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

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)

How many females are in this family? How many carriers? How many children were in generation two? How many offspring in generation three are affected by the trait? Pg. 80 Generation 1 Generation 2 Generation 3 Generation 4

How many females are in this family? 11 How many carriers? 7 How many children were in generation two? 5 How many offspring in generation three are affected by the trait? 2 Generation 1 Generation 2 Generation 3 Generation 4

Autosomal Dominant Trait- Many family members will show the trait in the pedigree Widow’s peak No Widow’s peak

On pg. 81, please create this pedigree and answer the following 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?

? ? ? Joe Jamie LL x ll 100% Ll LL ll Marie Kyle Ll ll Ll Ll x ll 50% Ll and 50% ll ? ? ? Yes, Kyle and Marie have Widow’s Peaks 50% should have Widow’s Peaks 50% should have NO Widow’s Peaks

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

On pg. 81, Fill in the genotypes of this incomplete pedigree On pg. 81, Fill in the genotypes of this incomplete pedigree. Shade if necessary. aa

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

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?

? ? ? Joe Mary Ff Ff Isabel Charles Pete Ff FF FF ff FF x Ff O%- No chance of any of their children having the disorder 50% will be carriers ? ? ?

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. X Y

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

X-linked Color Blindness- Recessive XMXM= Normal XMXm= carrier XmXm= CB XMY= Normal XmY= CB XmY XMXm XMXm XMXm XMXm XMY XmY On pg. 80, Fill in the genotypes of this incomplete pedigree. Shade if necessary. ? XmY XmY XMXM or XMXm

A karyotype is a picture of all chromosomes in a cell. X Y

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

In down syndrome a person has an extra copy of chromosome 21. In Klinefelter’s syndrome a male has an extra X (XXY).