Genetics The study of heredity How traits are passed on from one generation to the next.

Blended Inheritance In ancient times, people thought traits were an equal blend from each parent Blue eyes + black eyes = green eyes Could not explain Brown eyes + Brown eyes = blue eyes

Gregor Mendel Austrian monk who studied garden peas Determined the laws of heredity

Are some traits stronger than others? Mendel crossed pea plants with different traits. Parental(P) + Parental(P) = First Fillial(F1) Yellow peas + Green peas = All Green Round peas + Wrinkled peas = All Round

Parental Generation Green + Yellow Round Wrinkled First Fillial All Green All Round Second Fillial

Are some traits stronger than others? Results: When plants with two different traits (alleles) are crossed, one trait appears in the offspring. Dominant: Trait that appears always Recessive: Trait that is hidden by dominant

Are the recessive traits gone in F1? Mendel crossed the peas produced to see if the recessive (hidden) trait would appear. F1 + F1 = F2 Green + Green = 3 Green to 1 yellow Round + Round = 3 Round to 1 wrinkled

Parental Generation Green + Yellow Round Wrinkled First Fillial Mendel bred these together All Green Green +Green All Round Round + Round Second Fillial This is the ratio 3 Green 1 Yellow 3 Round 1 Wrinkled

Are the recessive traits gone in F1? Results Recessive traits (alleles) are present in F1, just hidden. Parents give alleles randomly to offspring.

The Law of Segregation Bb b B Gametes get one copy of an allele pair from a parent. b Bb B Parent Genes Gametes Round/wrinkled wrinkled Round

The Law of Independent Assortment Genes for different traits segregate independently during gamete formation.

The Law of Independent Assortment AaBb AB Ab aB ab Parent Genotype Gametes Round/wrinkled Green/yellow yellow/wrinkled Green/ Round yellow/Round Green/ wrinkled