INTRODUCTION TO GENETICS

Mendel 1850 ish –1865 wrote paper on work, no recognition Austrian Monk Educated at university; studied math and science; statistics Gardener; worked alone

Mendel used garden peas for his studies because: They have 7 contrasting traits They are self pollinating They produce many generations in a short time. They are easy to grow and maintain

Dominant and Recessive Pea Traits Dominant Traits Tall Colored Seed Coats Axial Flowers Green Pea Pods Inflated Pea Pods Yellow Peas Round Peas Recessive Traits Short White Seed Coats Terminal Flowers Yellow Pea Pods Constr-icted Pea Pods Green Peas Wrinkled Peas

Dominant and Recessive Pea Traits Seed Color Pod Appearance Seed Texture Pod color Flower Position Seed Coat Color

MENDEL’S PRINCIPLES OF INHERITANCE Skill MENDEL’S PRINCIPLES OF INHERITANCE

Law of Dominance -states that some alleles are dominant whereas others are recessive.

An organism with a dominant allele for a particular trait will always have that trait expressed. An organism with a recessive allele for a particular trait will only have that trait expressed when the dominant allele is not present

Genotype (genetic makeup) TT represents a homozygous dominant genotype. tt represents a homozygous recessive genotype. Tt represents a heterozygous genotype

Homozygous When an organism has two identical alleles for a particular trait . Ex. HH hh SS tt gg PP

Heterozygous When an organism has two different alleles for a particular trait . Ex. Hh Tt Ss Uu Pp Ww

Phenotype (physical characteristics) TT or Tt -would have a phenotype of tall tt -would have a phenotype of short.

Law of Segregation The two factors (genes) separate during the formation of egg or sperm. (only 1 for each trait in the gamete).

Law of Independent Assortment *The segregation of the alleles of one trait does not affect the segregation of the alleles of another trait. *Genes on separate chromosomes separate independently during meiosis.

____Gene ____Homozygous ____ Allele ____Heterozygous ____ Phenotype Part of the genetic information referring to a trait The 2 genes for a trait are the same, TT or tt The exact gene combination for a trait; Tt Genes that refer to an observable trait Appearance of the organism for a trait The two genes for a trait are contrasting; Tt ____Gene ____Homozygous ____ Allele ____Heterozygous ____ Phenotype ____ Genotype