Genetics Chapter 8
Gregor Mendel: Father of Genetics Genetics: study of heredity Heredity: passing traits from parent to offspring Used peas to study heredity
Why Peas? 1. Several Traits 2. Control mating 3. Small, grow easily, and matures quickly
Alleles: Different versions of a gene Ex: White and Purple Flowers
Mendel’s Experiment Monohybrid Cross: One pair of contrasting traits. Ex: Mating a plant with purple flowers with white flowers True-breeding: All offspring would have only one form of the trait Ex: Purple-flowering plant only has purple- flowered offspring
Mendel’s Experiments
Vocabulary Dominant: (A) Expressed in appearance when the individual has one copy Recessive: (a) Not noticeable in appearance when individual has one copy Individual must have two copies of recessive allele to express the trait Homozygous: AA or aa Heterozygous: Aa
More Vocabulary Genotype: Genetic make up (ex: Pp) Phenotype: Physical Appearance (ex: Purple flowers)
Punnett Square-predicts outcome of a cross 1 pair of contrasting traits btwn 2 individuals
Ratios
Test Cross
Law of Segregation Alleles for a trait separate when gametes are formed 50% chance that one allele will go into a gamete
Law of Independent Assortment Alleles of different genes separate independently of each other during meiosis
Dihybrid Cross: Cross that involve two traits