Mendel and His Peas Chapter 11 Lesson 1

Background The subject: pea plants Why? Reproduce quickly Easily observed traits Can control reproduction

Pollen (sperm cells) land on pistil (egg cells) Pollination Pollen (sperm cells) land on pistil (egg cells)

Self-pollination Pollen from one plant lands on pistil from same plant. True-breeding – results from self-pollination, offspring will have the same traits

Cross Pollination Pollen from one plant lands on pistil from a different plant.

What Mendel Did

Traits Studied Flower color – purple/white Seed color – green/yellow Seed shape – round/wrinkled

First-Generation Crosses

Second-Generation Cross

Mendel’s Conclusions Two genetic factors control every trait. One trait comes from sperm, one trait comes from egg.

Discovered Dominant and Recessive Traits Purple is dominant trait – a genetic factor that blocks another genetic factor.

Discovered Dominant and Recessive Traits White is recessive trait – a genetic factor that is blocked by a dominant trait.

Discovered Dominant and Recessive Traits Recessive is only seen when both factors are recessive.