Section 11-1: The Work of Gregor Mendel

1. Section 11-1: The Work of Gregor Mendel -The Father of Modern Genetics-

2. 1. Genetics • The scientific study of heredity • Every living thing contains hereditary information from its parent or parents • Passed down through generations

3. Who is Gregor Mendel? THIS GUY • A priest who worked in a monastery and as a high school teacher • In charge of the monastery garden • Worked with garden peas • Laid the groundwork for modern genetics

4. 2. Mendel’s Peas: Reproduction • The flower creates 2 types of pollen • Male: Sperm • Female: Egg cells • Fertilization • Joining of the male and female pollen • Produces a tiny embryo encased in a seed • Normally “Self Pollinating” • They inherit all their genetic information from one parent

5. Mendel’s Peas: Breeding • 3. Each of his pea plants were “True-Breeding” • If allowed to self pollinate they would produce identical offspring • Types of Pea Plants present: • Height • Tall Plants • Short Plants • Seed Color • Green Peas • Yellow Peas

6. Mendel’s Peas: The Cross Pollination • Wanted to produce seeds by joining male and female cells from two different plants • 4. Cross Pollination • Cut away pollen (male) from one plant and dusting the female flower with the male pollen • Made it possible to cross breed the plants and observe the offspring

7. Cross Pollination Diagram

8. Genes and Dominance: Vocab • 7. Traits • Specific characteristic present in an organism • EX: Hair Color • 6. Hybrid • Off spring of crosses between parents with different genetic traits • EX: Humans • 5. Genes • Chemical factors that determine traits; passed down from parent to offspring • EX: Hair Color • 8. Alleles • Different forms of a gene • EX: Red Hair, Brown Hair, etc.

9. Genetic Terms • The P (Parental) generation • The original pair of plants • The F1 (first filial) generation • The offspring of the P generation • The F2 (second filial) generation • The offspring of the F1 generation

10. Mendel’s Process • Studied 7 pea plant traits • Seed color or plant height variation • Each trait had 2 contrasts • EX: Height- Tall and Short • Mendel crossed plants with each of the contrasting traits and studied the offspring • This had very interesting results

11. Results of P Cross • When crossed all of the F1 generation plants displayed only one of the 2 traits • All plants were tall! • The other trait seemed to disappear • What happened?

12. Mendel’s Conclusions • #1. Biological inheritance is determined by factors passed from one generation to the next • 9. #2 .The Principle of Dominance • Some alleles are dominant and others are recessive • Dominant: Trait will always be expressed • 10. Recessive: Trait will be expressed only in absence of dominant trait

13. Traits of Pea Plants 11. Dominant Recessive Height- Short Seed Color- Green Seed Coat- White Pod Shape- Constricted Pod Color- Yellow Flower Position- Terminal Seed Shape- Wrinkled • Height- Tall • Seed Color- Yellow • Seed Coat- Gray • Pod Shape- Smooth • Pod Color- Green • Flower Position- Axial • Seed Shape- Round

14. Mendel’s Process • Mendel wanted to see if the recessive alleles had disappeared or were still present • 12. Allowed the F1 plant to self pollinate and created an F2 generation with odd results. • Resulted in 3 tall plants and 1 short plant • The recessive allele had reappeared!

15. Results of the F1 Cross • Resulted in 3 tall plants and 1 short plant • The recessive allele had reappeared! • 13. The recessive allele accounted for roughly ¼ of the total plants…but how did this happen? • Let’s look at the F1 cross in detail

16. F1 Cross-Explanation • 14. The alleles for height segregated or separated • The alleles for tall and short separated during the formation of the sex cells • 15. These sex cells are called “Gametes” • This allowed the recessive trait to cross pair with another recessive and be present

17. 16. F1 Cross Illustrated 17.Key T- Dominant t - Recessive Tt Tt T T t t tt Tt Tt TT

18. Exit Slip