Mendelian Genetics How Genetics Began Gregor Mendel Father
Mendelian Genetics
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.
● 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.
● 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.
The Results ● The resulting offspring had yellow seeds. The offspring from this first cross are called the first filial generation (F 1). ● 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. (F 2)
Results ● 3: 1 Ratio of yellow to green seeds.
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.
Vocabulary ● Dominant: Form of the trait that appeared. (Yellow- seeds in the F 1 generation). Represented by a capital letter. (A) ● Recessive: Form of the trait that was masked. (Green -seeds in the F 1 generation). Represented by a lower case letter. (a)
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.
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
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