Mendel and the Gene Idea

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Slide 1

Drawing from the Deck of Genes

What genetic principles account for the passing of traits from parents to offspring?

The “blending” hypothesis is the idea that genetic material from the two parents blends together (like blue and yellow paint blend to make green)

Slide 2

The “particulate” hypothesis is the idea that parents pass on discrete heritable units (genes)

Mendel documented a particulate mechanism through his experiments with garden peas

Slide 3

Fig. 14-1

Slide 4

Concept 14.1: Mendel used the scientific approach to identify two laws of inheritance

Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments

Slide 5

Mendel’s Experimental, Quantitative Approach

Advantages of pea plants for genetic study:

There are many varieties with distinct heritable features, or characters (such as flower color); character variants (such as purple or white flowers) are called traits

Mating of plants can be controlled

Each pea plant has sperm-producing organs (stamens) and egg-producing organs (carpels)

Cross-pollination (fertilization between different plants) can be achieved by dusting one plant with pollen from another

Slide 6

Fig. 14-2

TECHNIQUE

RESULTS

Parental

generation

(P)

Stamens

Carpel

1

2

3

4

First

filial

gener-

ation

offspring

(F1)

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Slide 7

Fig. 14-2a

Stamens

Carpel

Parental

generation

(P)

TECHNIQUE

1

2

3

4

Slide 8

Fig. 14-2b

First

filial

gener-

ation

offspring

(F1)

RESULTS

5

Slide 9

Mendel chose to track only those characters that varied in an either-or manner

He also used varieties that were true-breeding (plants that produce offspring of the same variety when they self-pollinate)

Slide 10

In a typical experiment, Mendel mated two contrasting, true-breeding varieties, a process called hybridization

The true-breeding parents are the P generation