Genetics The branch of biology that studies heredity

Gregor Mendel The Father of Genetics An Austrian Monk during the mid nineteenth century Used garden pea plants to make his discovery that traits are passed from parent to offspring

Important Vocabulary Trait- characteristics that are inherited Gamete- sex cells (ex..in humans sperm and egg) Fertilization- the uniting of male and female gametes Hybrid- the offspring of parent that has different forms of a trait (ex. Tall and short height)

Important Vocabulary

Mendel’s Discoveries The rule of unit factors : each organism has two factors that control each of its traits. The factors are called alleles. One allele is inherited from the female parent and one from the male parent.

Mendel’s Discoveries The rule of dominance: when a dominant allele is present you will see it. You will only see a recessive allele when there is no dominant allele present.

Mendel’s Laws The Law of Segregation states that alleles randomly pair during fertilization. The Law of Independent Assortment states that different traits are inherited independently of each other. Example seed shape and seed color have no influence on each other.

Monohybrid cross T- stands for tall t – stand for short Dominant traits are always written with a capital letter. Dominant alleles will always be seen if they are present. Recessive traits are always written with a lower case letter. One can only see a recessive trait when a dominant trait is not present. You must have two recessive alleles.

Phenotype- the way the offspring look The phenotype of the F1 generation of the monohybrid cross is all tall.

Genotype- the actual allele configuration of the offpring The genotype of the F1 generation is “all Tt” or “all heterozygous”-

Heterozygous vs. Homozygous Heterozygous means a dominant allele and a recessive allele is present. Examples: Tt, Yy, Pp Homozygous means there is only one form of the allele present. Examples: tt, TT, YY, yy, PP, pp Offspring can be either homozygous dominant (TT) or homozygous recessive (tt).

Monohybrid Cross Yy x Yy Y-Yellow pea y- green pea What is the phenotype of this F1 generation? What is the genotype of this F1 generation?