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 geneEx: 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