BiologyChapter 12 Section 1

Key Ideas Why was Gregor Mendel important for

modern genetics? Why did Mendel conduct experiments

with garden peas? What were the important steps in

Mendel’s first experiment? What were the important results of

Mendel’s first experiment?

Mendel’s Breeding Experiments Monk named Gregor Johann Mendel in

the 1800’s in Austria. Did breeding experiments with pea

plants. Modern genetics is based on Mendel’s

explanations for the patterns of heredity in garden pea plants.

He studied to be a priest. He went to the University of Vienna. He studies science.

Lived the rest of his life in a monastery, where he taught high school and cared for a garden.

Most of Mendel’s experiments involved crossing different types of pea plants.

To cross means to mate or breed two individuals.

He crossed a plant with purple flowers with one that had white flowers. All of the offspring had purple flowers.

But when these flowers were crossed, some offspring had white flowers and some had purple flowers.

Since the white flower reappeared in the second group (generation) he decided to investigate this strange occurrence.

Why Did He Use Pea Plants? Contrasting Traits Self-Pollination Easy to Grow

Contrasting Traits Physical features that are inherited are

called characters. A trait is one of several possible forms of

a character. The offspring of a cross between parents

that have contrasting traits is a hybrid.

Self-Pollination Each pea plant contains male and female

reproductive parts. This allows them to self-pollinate.

The can also reproduce by cross-pollination. This happens when pollen from one pants is carried by insects or other means to the flower of another plant.

To make sure the plants couldn’t self-pollinate, he removed the male parts but did not remove the female parts. He dusted the female parts with pollen from another plant.

Easy to Grow The small plants that need little care

and they mature quickly. They also produce many offspring.

7 Characters Studies By Mendel Flower Color Seed Color Seed Shape Pod Color Pod Shape Flower Position Plant Height

Mendel’s First Experiment Carried it out with a monohybrid cross

(one purple and one white) He allowed each one to self-pollinate

first and create a “true-breed”. They are called the parental generation (P generation).

Then he crossed 2 P generation plants and called the offspring the first filial generation (f1 generation)

He allowed the f1 generation to self-pollinate and produce new plants. He called them f2 generation.

He discovered that in the f2 generation the white flowers reappeared.

Ratios in Mendel’s Results For each of the 7 characters that Mendel

studies, he found a 3-to-1 ratio of contrasting traits in the f2 generation.