Gregor Mendel ( ) Responsible for the Laws governing Inheritance of Traits Genetics – the study of heredity.

Mendel’s Experimental Methods Mendel hand-pollinated flowers using a paintbrushMendel hand-pollinated flowers using a paintbrush –He could snip (cut) the stamens to prevent self- pollination He traced traits through the several generationsHe traced traits through the several generations

Seed Shape Flower Position Seed Coat Color Seed Color Pod Color Plant Height Pod Shape Round Wrinkled Round Yellow Green Gray White Smooth Constricted Green Yellow Axial Terminal Tall Short YellowGraySmoothGreenAxialTall Section 11-1 Figure 11-3 Mendel’s Seven F 1 Crosses on Pea Plants Go to Section: Different Traits of the Pea Plant

 Mendel stated that physical traits are inherited as “particles”  Mendel did not know that the “particles” were actually Chromosomes & DNA Particulate Inheritance

Alleles – different form of a gene Genes – The chemical factors that determine traits

The Principle of Dominance States that some alleles are dominant and other are recessive. Dominant-genes that are expressed Recessive-genes that are not expressed if a dominant gene is present

P Generation F 1 Generation F 2 Generation TallShortTall Short Section 11-1 Principles of Dominance Go to Section: The Trait for Tallness

Applying the Law of Segregation Probability – the likelihood that a particular event will occur

Section 11-2 Tt X Tt Cross Go to Section: Punnett Squares The gene combinations that might Result from a genetic cross.

Section 11-1 Interest Grabber continued Go to Section: Parents Long stems  short stems Red flowers  white flowers Green pods  yellow pods Round seeds  wrinkled seeds Yellow seeds  green seeds First Generation All long All red All green All round All yellow Second Generation 787 long: 277 short 705 red: 224 white 428 green: 152 yellow 5474 round: 1850 wrinkled 6022 yellow: 2001 green Mendel’s Outcomes

Punnett Squares – Cont. Homozygous – Identical Alleles ex. TT, tt (“Purebred”) Heterozygous – 2 different Alleles ex.Tt (“Hybrid”) Phenotype – Physical Characteristics Genotype – Genetic Make-up or combination of alleles TT, Tt, tt