1. Mendelian Genetics

2. How Genetics Began Gregor Mendel Father of genetics
Austrian monk & plant breeder
In 1866, published findings on the method of inherence in garden pea plants.
Genetics: The science of heredity.
Heredity: The passing of traits of the next generation.

3. Mendel studied pea plants
Pea plants consistently produce off-spring with only one form a trait.
Pea plants reproduce by self-fertilization.
Mendel noticed that some pea plants always produced green seeds, while others always produced yellow seeds.

4. Mendel performed cross-pollination by transferring male gametes from the flower of a green-seed plant to the female organ of a flower from a yellow- seed plant.
He called the green-seed plant & the yellow seed plant the parent generation, also known as the P generation.

5. The Results
The resulting offspring had yellow seeds. The offspring from this first cross are called the first filial generation (F1).
Mendel wanted to know: is the green-seed trait gone, or is it just hidden?
Allowed the plants to grow & self-fertilize. This generation of seeds is called the second filial generation. (F2)

6. Results
3:1 Ratio of yellow to green seeds.

7. Mendel’s Conclusions
2 forms of the seed trait in the pea plants (yellow-seed & green-seed).
Each form is controlled by a factor called an allele.
Allele: An alternative form of a single gene passed from generation to generation.
The gene for yellow seeds & the gene for green seeds are different forms of a single gene.

8. Vocabulary
Dominant: Form of the trait that appeared. (Yellow-seeds in the F1 generation). Represented by a capital letter. (A)
Recessive: Form of the trait that was masked. (Green-seeds in the F1 generation). Represented by a lower case letter. (a)

9. Vocabulary
An organism that has 2 of the same alleles for a particular trait is homozygous for that trait. (AA or aa)
An organism that has 2 different alleles for a particular trait is heterozygous for that trait.(Aa). The dominant allele is observed.

10. Vocabulary Genotype: The organism’s pair of alleles. (AA, Aa, aa)
Phenotype: The observable characteristics of an allele pair.
AA = Yellow-seed
Aa= Yellow- seed
aa = Green-seed