Genetics

What is Genetics? Heredity: The passing of traits from

parents to offspring.

Genetics: the scientific study of heredity.

Gregor Mendel Born in 1822

When he was 21 he entered an Augustinian monastery, where he became a math and science teacher.

Began studying the plants.

Mendel’s Plant Height Experiment Mendel started his experiment with pea

plants. Mendel used purebred plants. A purebred plant is one that always

produces offspring with the same form of a trait as the parent.

Mendel’s Plant Height Experiment1. He bred pea plants so they always produce offspring with heights like parents:

Tall parent: tall offspring Short parent: short offspring

Mendel’s Plant Height Experiment Then, he bred a tall pea plant with a

short pea plant He found that the offspring were all tall.

Mendel’s Plant Height Experiment Then he bred two of these tall offspring

together There were some tall and some short

offspring. This lead him to think that the peas had

a trait for tallness and shortness.

Traits He called them dominant and

recessive traits. A dominant trait is one that prevents

another from appearing or showing themselves in the offspring

A recessive trait is one that will not appear when a dominant trait is present.

An organism with a pure trait had ALL dominant or ALL recessive traits.

A pure bred is an organism that always produces offspring with the same form of a trait as the parent.

Mendel’s Peas Mendel studied six other traits in pea

plants.

Genes Today we know Mendel’s traits as genes.

A dominant gene (represented by a capital letter) covers up or hides a recessive gene (represented by a lower case letter)

Genes Genes are inherited in pairs – one gene

from each parent.