The Laws of Inheritance

Learning Goals

1. Introduce the laws of inheritance

2. Introduce vocabulary terms used in genetics

Review

Genes are made of DNA

Segment of DNA is called a gene

Gene is responsible for traits

Gregory Mendel

Austrian Monk in 1800’sStudied Plants (pea plants)Founded the “Laws of Inheritance”

Pea Plant Traits

Pea plant traits: Flower colorPea pod colorTexture of seed

Mendel’s Experiment

1. Crossed opposite traits (purple x white)

2. Offspring were called3. Self pollinated the F1 offspring4. Second generation were called

P generation

F1 generation

F2 generation

Results:

Some traits were dominant and some recessive

3 Laws of Inheritance

1. Principle of Dominance2. Principle of Segregation3. Principle of Independent Assortment

Principle of Dominance

One trait is masked by another trait

There are 2 genes per trait:Dominant trait shows over the recessive trait

Purple is dominant over white

Purple Gene + White Gene = Purple Flowers

White Gene + White Gene = White Flowers

Purple Gene + Purple Gene = Purple Flowers

Principle of Segregation

The 2 genes separate during gamete formation

Parent can pass on either gene to offspring

White Purpleor

Principle of Independent Assortment

Genes separate independently during gamete formation

Each trait is independently inherited

Seed shape has nothing to do with seed color

Terms to Know

Homozygous- The two genes are the same

Heterozygous- The two genes are different

Exit Slip

List the 3 laws of inheritance:

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