1. Intro to Genetics

2. What is genetics? The study of heredity Ex. height, eye color
Traits – any characteristic that can be passed from parent to offspring
Ex. height, eye color
Heredity – passing of traits from parent to offspring (children)

3. What are genes? Specific sequences of DNA Location:
Genes are located on homologous chromosomes

4. Father of Genetics: Background on Gregor Mendel: Austrian monk
Studied science & math at the University of Vienna Formulated the Laws of Heredity in the early 1860's Did a statistical study of  traits in garden peas over an eight year period

5. What did Mendel do?
He cross-pollinated pea plants

6. What traits was he looking for?

7. What did Mendel do with flower color?
He cross-pollinated pea plants ( purple and white)
F1 generation – first offspring of P ( parental generation)

8. F1 x F1
Mendel then crossed two of his F1 plants and tracked their traits; known as an F1 cross

9. Mendel's Results When 2 hybrids (Tt) were crossed:
1)75% (3/4) of the offspring showed the dominant trait
2) 25% (1/4) showed the recessive trait; always a 3:1 ratio
3)The offspring of this cross were called the F2 generation

10. What did Mendel do next?
Mendel then crossed a pure ( TT or tt) & a hybrid ( Tt) from his F2 generation; known as an F2 or test cross

11. Results of Mendel’s Testcross
50% (1/2) of the offspring in a test cross showed the same genotype of one parent & the other 50% showed the genotype of the other parent; always a 1:1 ratio

12. Important terms to know!!!
Genotype - gene combination for a trait (e.g. RR, Rr, rr) you cannot see this
Phenotype - the physical feature resulting from a genotype (e.g. tall, short)
The trait that is expressed or shows

13. More terms!!!
Gene – segment of DNA on a chromosome that controls a particular hereditary trait
Allele –two forms of a gene (paired)
Ex: T= tall and t= short ( the letters are examples of alleles)

14. More terms!!!!
Dominant - stronger of two genes; represented by a capital letter (R)
Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r)

15. Homozygous genotype - gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure  (homo=same,alike,man)
Heterozygous genotype - gene combination of one dominant & one recessive allele    (e.g. Rr); also called hybrid (hetero=different, other, opposite)

16. Types of Genetic Crosses
Monohybrid cross - cross involving a single trait e.g. flower color
Dihybrid cross - cross involving two traits e.g. flower color & plant height

17. To do crosses of traits we use:
Punnett Squares!!!

18. Punnett Square For this punnett square: B= purple b=white Phenotype:
Male: Purple
Female: Purple
Genotype:
Male: Bb ( heterozygous or hybrid)
Female: Bb ( heterozygous or hybrid)

19. Results of Bb x Bb:
Genotype:
1BB:2Bb:1bb
Phenotype:
3 purple: 1 white