1. Fundamentals of Genetics

2. Early Genetics Gregor Mendel- Austrian monk—mid 1800s “Father of Genetics” - studied garden peas Pisum sativum

3. Reasons for Mendel’s Success 1. Chose subject carefully- could manipulate which plants were crossed 2.Careful Research- studied one variable at a time * carefully controlled each experiment * analyzed data mathematically

4. Ex: Purple flowers X White Flowers P 1 Purple flowers X White flowers F 1 All Purple flowers (self-pollinate) F 2 3 Purple flowers: 1 White flower

5. Conclusions Mendel concluded that there must be 2 factors controlling each trait these “factors” are now called alleles Recessive- allele that is masked by dominant (does not show up in F1) Dominant- allele that masks other trait, or appears in F1

6. Mendel’s Laws 1.Law of segregation- states that a pair of factors is segregated, or separated, during the formation of gametes *when gametes unite, offspring will have two factors for a specific trait

7. Mendel’s Laws 2.Law of Independent Assortment- factors for different characteristics are distributed to gametes independently *only observed for genes on separate chromosomes or located far apart on same chromosome

8. Genetic Cross Terminology Genotype- genetic make-up of an organism (Ex: PP, Pp, pp) Phenotype- appearance of an organism (Ex: tall or short, purple or white flowers)

9. Genetic Cross Terminology Homozygous- both alleles of a pair are alike (PP or pp) Heterozygous- alleles in a pair are different (Pp)

10. Genetic Cross Terminology Probability- likelihood that an event will occur Probability = _____________________ can be written as a fraction, decimal, or percentage

11. Monohybrid Crosses Mono = “one” cross involving only one trait to predict probability of offspring inheriting certain traits, biologists use Punnett squares

12. 3 Types of Monohybrid Cross 1.Homozygous x Homozygous 2.Homozygous x Heterozygous 3. Heterozygous x Heterozygous

13. Test Crosses To determine genotype of an unknown individual that has a dominant phenotype, a test cross is performed to do this, cross the unknown individual with a homozygous recessive individual

14. Incomplete Dominance offspring have a phenotype in between that of the parents 2 or more alleles influence phenotype (get an intermediate phenotype)

15. Incomplete Dominance Example: four o’clocks (flowers) R = red flowers r = white flowers Red x White

16. Codominance both alleles for a gene are expressed in a heterozygous offspring Example: Roan colored horses R= red R’=white Individual that is RR’ will have both white and red hairs in coat.

17. Dihybrid Crosses Di = “two” cross involving two traits more complicated- more squares to fill in because there are more possible allele combinations

18. Types of Dihybrid Crosses 1.Homozygous x Homozygous 2. Heterozygous x Heterozygous 9 different genotypes 4 different phenotypes in a 9:3:3:1 ratio