More on Genetics BY: BRIANNA SHIELDS

Do Now 1. How do you describe this genotype: RR? (homozygous recessive, heterozygous, etc.) 2. If having hair in your ears is a dominant trait, and you have the gene combination Hh, will you have hair in your ears? 3. What do you call the physical appearance that an organism shows due to it’s gene combination (the way an organism looks)?

GOAL To use punnett squares to predict the traits of offspring To become familiar with pedigree charts

Review Brown eyes is dominant. Blue eyes is recessive. The mother is heterozygous and the father is heterozygous. What percentages of blue-eyed and brown eyed offspring will they get?

Bb x Bb B= Brown b=Blue B b BB Bb B Bb bb b Genotypes: 25% Homozygous Dominant BB 50 % Heterozygous Bb 25% Homozygous Recessive bb B b BB Bb B Bb bb b Phenotypes 75% Brown Eyed 25% Blue Eyed

Review Having a short middle toe is a dominant trait. Having a long middle toe is recessive. If a heterozygous male and a homozygous recessive female have a child- what is the probability that the offspring will have a long middle toe?

Mm x mm M m Mm mm m Mm mm m M= Short Middle Toe m= Long Middle Toe Genotypes: 50 % Heterozygous Mm 50% Homozygous Recessive mm Mm mm m Mm mm m Phenotypes 50% Short middle toe 50% Long middle toe

Create a punnett square: A couple would like to have children- however, the husband has cystic fibrosis. Having cystic fibrosis is a recessive trait. The wife, however, does not have cystic fibrosis- but she is a carrier for the disease (she is heterozgyous). What are their chances for having a child with cystic fibrosis?

Bb x bb B= Normal b=Cystic Fibrosis B b Bb bb b Bb bb b Genotypes: 50 % Heterozygous Bb 50% Homozygous recessive bb Bb bb b Bb bb b Phenotypes 50% Carrier-Healthy 50% cystic fibrosis

More Genetics Terms Carrier When an individual is heterozygous (carries the disease gene), although they don’t actually have the disease (Cc).

More Genetics Terms Pure Bred Homozygous recessive (bb) and Homozygous dominant (BB) AKA True breeders

More Genetics Terms Hybrid Heterozygous individuals

More Genetics Terms Sex Chromosomes Out of your 46 chromosomes - 2 of them are sex chromosomes Male = XY Female = XX

Punnett Example: XX x XY Genotypes: 50 % XX 50% XY XX XX X XY XY Y Phenotypes 50% Boy 50% Girl X= Female Y=Male

Normal Human Karyotype

Chromosome Disorders Turner’s Syndrome Monosomy X Female Short stature Skin folds on the neck Lack of sexual development Small, sterile, minor malformations

Chromosome Disorders Klinefelter’s Syndrome XXY Male Chest malformations Poor sexual development Low fertility Decreased intelligence

Chromosome Disorders XYY Syndrome Male prisoners Increased violence Above-average height Subnormal intelligence

Chromosome Disorders XXX Syndrome Increased mental retardation Sterility Metafemale

Chromosome Disorders Trisomy 21- extra chromosome Mental retardation Developmental Problems Characteristic features

Chromosome Disorders: Websites What Can Our Chromosomes Tell Us? Special Child: Disorder Zone Archives

Inheritance of Abnormal Genes Is this a recessive or a dominant disease gene?

Inheritance of Abnormal Genes

Genetics Websites OLogy: The Gene Scene DNA is an Instruction Manual Understanding Genetics: Human Health and the ... Gene Safari

Chromosomes in the Cell What Are Chromosomes?

Pedigree Charts

Genetics Assessment --> Complete the Punnett Square Word Problems --> Genetics Lab- Look at characteristics of classmates --> Worksheet: “Should this Dog be Called Spot?” Practicing Punnett Squares on the Internet

DO NOW Get out your homework Go over your answers with your SEAT PARTNER If you aren’t done, FINISH IT!! We will go over the answers together in a few minutes