Inheritance

Mendel – Found that alleles show up in predictable patterns and that some alleles show up more often than others•Homozygous (Pure-Breeds) - both alleles are the same (PP or pp)

•Heterozygous (Hybrids) - both alleles are different (Pp)

•Carriers – heterozygotes for a recessive trait

HomozygousPure-Breed Crosses result in: 100% chance dominant phenotype

Heterozygous

Hybrid Crosses result in: 75% chance dominant phenotype25% chance recessive phenotype

Compare

What makes the difference between a 100% chance of the dominant phenotype and only 17% chance of the dominant phenotype ?

Pure-Breed Crosses result in: 100% chance dominant phenotype

Hybrid Crosses result in: 75% chance dominant phenotype25% chance recessive phenotype

Generations

First Generation: First Filial (F1)

Second Generation: Second Filial (F2)

Third Generation: Third Filial (F3)

Parents: P1 generation

Chance of Inheritance

100% chance 75% chance 75% chance 0% chance

First Generation: First Filial (F1)100% chance dominant phenotype

Second Generation: Second Filial (F2)75% chance dominant phenotype

Third Generation: Third Filial (F3)63% chance dominant phenotype

Parents: P1 generation

Alleles can be tracked through multiple generations and probabilities determined

Inheritance

Alleles can be tracked through multiple generations and probabilities determined

First Generation: First Filial (F1)100% chance dominant phenotype

Second Generation: Second Filial (F2)75% chance dominant phenotype

Third Generation: Third Filial (F3)63% chance dominant phenotype

100% chance 75% chance 75% chance 0% chance

Parents: P1 generation

Practice

• Video on making punnett squares• In your notebook complete the Probability

(Long vs Short Big Toe) Lab.

Linked genes (genes that occur very close to one another on a chromosome) are the exception

Write these 4 ideas from Mendel in your notebook

Summary of Mendel’s Principles

Gregor Mendel’s work forms the basis of modern genetics:• Genes are passed from parent to offspring

• Some forms of genes (alleles) are dominant while others are recessive

• Genes randomly segregate (independent assortment) when gametes are formed

• The alleles for different genes usually segregate independently of one another

DNA Chromosomes• From Chromosome to DNA• How DNA is packaged animation• Meiosis is how DNA is copied and

sepereted to make gametes (sperm and egg)• Complete cornell notes for the

Meiosis video and glue onto page ___ of your notebook– What is the purpose of Meiosis and Mitosis?

• Complete the lab “Why don’t we look like our siblings” and glue in your notebook

Solving Punnett SquaresIf a round pea plant (AA) is crossed with a wrinkled pea plant (aa), what percent of the offspring will be:• Round?• Wrinkled?

If two heterozygous round pea plants are crossed, what percent of the offspring will be:• Round?• Wrinkled?

If a heterozygous round pea plant is crossed with a homozygous wrinkled pea plant, what percent of the offspring will be:• Round?• Wrinkled?

Solve these in your notebook.