Chapter 8 Mendel & Heredity

Chapter Overview 8.1 Mendel’s Experiment 8.2 Theory and Law of Heredity 8.3 Punnett Squares 8.4 Complex Patterns of Heredity

Topic #1-8.1 Origin of Genetics 1800s before DNA Gregor Mendel Austrian monk intrigued with “heredity” Passing of traits from parents to offspring Designed an experiment to show how “genes” were passed down Bred pea plants for color patterns 7 years Observed inheritance patterns

Topic #2- Mendel’s Experiment Monohybrid Cross 1 trait flower color Based on this experiment he came up with 4 hypotheses…

Mendel’s Hypotheses 1. Alternating forms of genes called alleles

Mendel’s Hypotheses 2. For each trait organism has 2 alleles Same 2 alleles = homozygous (AA, aa) Different alleles = heterozygous (Aa)

Mendel’s Hypotheses 3. When only 1 of the 2 traits in a heterozygous organisms is visible the allele is dominant (R) the non visible is recessive (r) You only see “white” when There are 2 small letters (homozygous recessive) Because the large letter isnt there to block it from showing

Mendel’s Hypotheses 4. The 2 alleles for a character separate during meiosis (gametes) Principle of segregation!!

Topic #3- What Mendel’s Experiment Show Us Today Every organism has a genotype Genetic makeup (AA, Aa, aa) Every organism has a phenotype Observable (Purple, Purple, White)

REVIEW What are the genotypes for What is a Genotype? Homozygous dominant: Heterozygous: Homozygous recessive: What is a Genotype? What is a Phenotype? What is an Allele? AA Aa aa

Monohybrid Practice problems Cross H. Dominant X Heterozygous Cross H. Recessive X Heterozygous Cross Heterozygous X Heterozygous Cross H. Dominant X H. Recessive Practice Worksheet