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Section 11-1: The Work of Gregor Mendel

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Presentation on theme: "Section 11-1: The Work of Gregor Mendel"— Presentation transcript:

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 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- Tall
Seed Color- Yellow Seed Coat- Gray Pod Shape- Smooth Pod Color- Green Flower Position- Axial Seed Shape- Round Height- Short Seed Color- Green Seed Coat- White Pod Shape- Constricted Pod Color- Yellow Flower Position- Terminal Seed Shape- Wrinkled

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 Tt Tt T t T t TT Tt Tt tt 17.Key T- Dominant
t - Recessive Tt Tt T t T t TT Tt Tt tt

18 Exit Slip

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