GENETICS Gregor Mendel: The Father of Genetics PUNNETT SQUARES AND HEREDITY

MENDEL Austrian Monk Interested in Biology Bred Pea Plants for specific traits Was able to show that certain traits were “inherited”—meaning they were passed down from one generation to the next

Genetics Heredity BIOLOGICAL STUDY of Heredity Passing on of a characteristic from parents to offspring.

Pea Plants Reproduce Sexually, which means egg and sperm. Mendel studied seven traits of pea plants

Setting up a Cross CC CC AA B B A=Parent 1 Alleles C=Offspring Genotype B=Parent 2 Alleles

Setting up a Cross Basic Terminology P 1 = Parents F 1 = 1 st Generation of Offspring F 2 = 2 nd Generation of Offspring

Setting up a Cross Basic Terminology Dominant Allele: Only need only copy to be expressed phenotypically.  Uppercase letter = dominant allele Recessive Allele: Need two copies to be expressed phenotypically.  Lowercase letter = recessive allele NOTE: Use letter of dominant trait for cross.

Homozygous Dominant x Homozygous Recessive Dominant is Round Recessive is Wrinkled Monohybrid Cross: Seed Shape RR RR r r rr Rr Rr Phenotype(s): Parent 1: Parent 2: Offspring: Genotype(s): Parent 1: Parent 2: Offspring: Round Seed Wrinkled Seed Round Seed R r R r

Y Y y y yy Yy y Phenotype(s): Parent 1: Parent 2: Offspring: Genotype(s): Parent 1: Parent 2: Offspring: Yellow Seed Green Seed ½ green, ½ yellow Y y y ½ Y y, ½ y y Heterozygous x Homozygous Recessive Dominant is Yellow Recessive is Green Monohybrid Cross: Seed Color y y y

G G g g Gg g Phenotype(s): Parent 1: Parent 2: Offspring: Genotype(s): Parent 1: Parent 2: Offspring: Green Pod ¾ Green, ¼ Yellow G g ¼ GG, ½ Gg, 1/4 gg Heterozygous x Heterozygous Dominant is Green Recessive is Yellow Monohybrid Cross: Pod Color g g GGG

I I I i Ii i Phenotype(s): Parent 1: Parent 2: Offspring: Genotype(s): Parent 1: Parent 2: Offspring: Inflated Pod Inflated I i I ¼ I I, ¾ I i Heterozygous x Homozygous Dominant Dominant is Inflated Recessive is Constricted Monohybrid Cross: Pod Shape i I III

A few things to keep it simple…. Homozygous Recessive (2 recessive alleles) Homozygous Dominant (1 recessive allele) Heterozygous (1 dominant, 1 recessive allele) Letter for cross is determined by the first letter of the dominant allele. Capital Letter always comes first. Parent #1 Goes across the top of the punnett square and is mentioned first in the cross. Parent #2 Goes down the side of the punnett square and is mentioned second in the cross.