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