Gregor Mendel and His Peas

1. Gregor Mendel and His Peas A true story about an Austrian monk and how he became THE FATHER OF GENETICS

2. Peas, Peas, look at all the pretty peas Once upon a time… There was an Austrian monk named Gregor Mendel. He was young, about 21, when he was tasked with tending the monastery’s garden.

3. Now Gregor noticed some interesting things…. He observed how they grow, and how some peas looked very similar to each other while some looked completely different! Great Scott! Look at all these different peas!

4. Gregor observed 7 different kinds of pea plants…. Each time the peas had contrasting traits. There was…. • Tall plants and short plants (long or short stems) • Green pods and yellow pods • Inflated pods or constricted pods • Smooth seeds or wrinkled seeds • Green seeds and yellow seeds • Axial flowers and terminal flowers • And finally, pretty purple flowers and pretty white flowers

5. But Gregor wanted to know more… So Gregor, went to the University of Vienna to learn more. He studied science and statistics. Then FINALLY he got to return to his precious peas.

6. So Gregor got to work! Gregor worked his little scientist hands to the bone! He collected seeds from all his pea plants and recorded what characteristics the parent plant had.

7. He carefully made sure to control what pollen went where • Pollination- pollen is transferred to the stigma • Anthers- where pollen is produced (male) • Stigma- female reproductive part of a flower • Self-Pollination- pollen lands on the stigma of the same plant • Cross Pollination- pollen comes from a different plant

8. He sometimes put pollen on the stigma of the same plant • Self-pollination- Pollen and stigma from the same plant

9. Or sometimes… he chose to use pollen from a different plant • Cross pollination- Pollen and stigma from different plants

10. He discovered what we call the Law of Segregation • A pair of alleles is segregated (separated) during the formation of gametes • Remember! Genes occur in pairs! • One from the mother and one from the father father mother

11. Then he planted his beautiful seeds! He noticed that purple flowering plants came from the seeds from purple flowering plants, but to his surprise he saw that white flowering plants also sometimes came from purple flowering plants! How could that be! What he’ll soon find is the Law of Dominance!

12. First he tried crossing 2 pure contrasting traits (P-Generation) P GG x gg G G Key: G=green g= yellow g G g G g F1 Phenotype: 100% green Genotype: 100% heterozygous g G g G g

13. Then he tried crossing the F1 generations and the yellow peas returned! Ggx Gg F1 G g Key: G=green g= yellow G G G G g F2 Phenotype: 3:1 75% green 25% yellow Genotype: 1:2:1 25% homozygous GG 50% heterozygous 25% homozygous gg g G g g g Some genes must be dominant to other genes!

14. He discovered the Law of Dominance Test Cross • Is the plant homozygous or heterozygous ? • Perform a test cross! • Crossing the genotype in question with a homozygous recessive

15. Practice! GG or Gg? ?x gg P Key: G=green g= yellow g G g G g F1 Phenotype: 100% green Genotype: 100% heterozygous g G g G g

16. Practice! GG or Gg? P ?x gg Key: G=green g= yellow F1 Phenotype: 50% green 50% yellow Genotype:

17. And always remember….Give PEAS a Chance!