1. Gregor Mendel (1822-1884) The Father of Genetics Mendelian Genetics
3/27/2017
Gregor Mendel ( )
The Father of Genetics
This has been modified from the original ppt Oct. 2011
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2. Gregor Johann Mendel Austrian monk
Mendelian Genetics
3/27/2017
Gregor Johann Mendel
Austrian monk
Studied the inheritance of traits in pea plants
Developed the laws of inheritance
Mendel's work was not recognized until the turn of the 20th century

3. copyright cmassengale
Mendelian Genetics
3/27/2017
Gregor Johann Mendel
Between 1856 and 1863, Mendel cultivated and tested thousands of pea plants
He found that the plants' offspring retained traits of the parents
copyright cmassengale

4. Particulate Inheritance
Mendelian Genetics
3/27/2017
Particulate Inheritance
Mendel stated that physical traits are inherited as “particles”
Mendel did not know that the “particles” were actually Chromosomes & DNA
copyright cmassengale

5. copyright cmassengale
Mendelian Genetics
3/27/2017
Why peas, Pisum sativum?
Can be grown in a small area
Produce lots of offspring
Produce pure plants when allowed to self-pollinate several generations
Can be artificially cross-pollinated
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6. Mendel and His Peas Mendel tested 7 traits: Flower color
Flower position
Seed color
Seed shape
Pod shape
Pod color
Plant height

7. Mendel and His Peas
Mendel crossed flowers that were true-breeding for each characteristic.
He crossed a purple (PP) flowered plant with a white (pp) flowered plant. (Parent Generation)

8. Mendel and His Peas
Purple Parent (PP)
The first generation (F1) of plants all had purple flowers.
Where did the white color go??
White Parent (pp)
  (Pp)   
(Pp)
   (Pp)

9. Mendel and His Peas
Mendel took two of his first generation (F1 x F1) purple flowered plants and crossed them together.
In the second generation (F2) he had 3 purple flowered plants, and 1 white flowered plant.
Purple Parent (Pp)
Purple Parent (Pp)   
(PP)
  (Pp)
  (Pp)
  (pp)

10. Mendel and His Peas
Mendel noticed in the first generation, all of the white flowers seemed to disappear.
He called this a recessive trait.
The white color faded into the background at first.
It showed up in the next generation when he pollinated the flowers.

11. Mendel and His Peas
The color (purple) that seemed to mask over the recessive color was named the dominant trait.

12. Mendel and His Peas
Mendel was responsible for figuring out that each plant carried two sets of instructions for each characteristic (one from the “mom” and one from the “dad”).
Like many scientists, his work was not accepted until after his death.

13. Let’s Review
1. If you crossed a true-breeding black rabbit with a true-breeding white rabbit, all of the offspring would be black. Which trait is dominant in rabbits: black fur or white fur?
2. Which trait is recessive?

14. Answer
Black Rabbit (BB)
The trait for black fur is dominant over the trait for white fur. The white fur trait is recessive.
White Rabbit (bb)
  (Bb)
(Bb)

15. Google’s tribute to Mendel July 2011

16. Science Humor

17. Mendel and His Peas Vocabulary
Heredity- the passing of traits from parent to offspring.
Self-pollinate- A plant is often able to pollinate by itself because it contains both the male and female reproductive structures. This only requires 1 parent.

18. Mendel and His Peas
3. True-breeding- all of the offspring will have the same trait as the parent when self-pollinated
First-generation- the very first set of offspring from two parents
Dominant trait- the trait observed when at least one dominant allele for a characteristic is inherited

19. Mendel and His Peas
6. Recessive trait- a trait that is apparent only when two recessive alleles for the same characteristic are inherited
Genes- a segment of DNA that carries hereditary instructions and is passed from parent to offspring
Alleles- multiple forms of the same gene

20. Mendel and His Peas
Genotype- an organisms inherited combination of alleles
10. Phenotype- an organisms inherited appearance