What is Genetics?

2. Genetics: Study of heredity Heredity: passing of traits from parent to child Traits and genes are inherited from previous generations What is Genetics?

3. Gregor Mendel • “Father of Genetics” • Famous for pea plant studies • Mendel studied seven pea traits such as: • 1) Seed Color (yellow or green) • 2) Flower Color (purple or white) • 3) Seed texture (smooth or wrinkled)

4. Dominant traits: hid the expression of weaker traits • Recessive traits: hidden by the dominant trait • Example: Tall Pea x Short pea = 100% Tall pea

5. Which traits are dominant?

6. Gregor Mendel • Test 1: • Mendel crossed pure purple with pure white plants • F1 generation: 100% Purple • Test 2: • F1 purple crossed with another F1 purple • F2 generation: 75% purple, 25% white • Conclusion: 1 form of a trait prevents the expression of another

7. Chromosomes and Genes • Gene: Segment of DNA that controls a trait • Every trait has two genes (from mom and dad) • Allele: Alternative forms of a gene • Letters used to abbreviate alleles • Dominant Allele = Capital letters • Recessive Allele = Lowercase letters • Dominant alleles hide recessive alleles

8. Phenotype: Actual expression of an gene • Phenotype = Purple flower • Genotype: Genetic makeup of an organism • Ex: 2 dominant alleles • Genotype = PP • Genotype determines phenotype Common Definitions

9. Common Definitions • Homozygous: Combination of two same alleles • Ex: PP (homozygous dominant) • Ex: pp (homozygous recessive) • Heterozygous: Combination of 2 different alleles • Ex: Pp (heterozygous)

11. Quick Review • Mendel started work in genetics by studying peas • Each trait is determined by two alleles (one from each parent) • Dominant alleles hide recessive alleles