3.  Independent Assortment- Genes that segregate (separately) independently do not influence each other's inheritance.  The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes.

4.  Mendel did a two-factor (trait) cross to see if the separation of one pair of alleles affects the separation of another pair of alleles. Instead of crossing a yellow seed with a green seed; he observed seed color and seed shape together  Seeds that are round (R) and yellow (Y) are dominant to seeds that are wrinkled (r) & green (y)

5.  True-breeding round & yellow (RRYY)seeds were crossed with true breeding wrinkled and green seeds (rryy)  The result: All individuals in the F 1 generation were round & yellow

6. The Two Factor Cross: F2  Heterozygous F1 plants (RrYy) were crossed with each other to determine if the alleles would segregate from each other in the F2 generation. RrYy × RrYy

7.  The Punnett square predicts a 9 : 3 : 3 :1 ratio in the F2 generation  9 round & yellow: 3 round & green: 3 wrinkled & yellow: 1 wrinkled & green

8.  The results of the experiment: some seeds were round and yellow some seeds were wrinkled and green some seeds were round and green some seeds were wrinkled and yellow  Mendel had discovered the principle of independent assortment  Independent Assortment explains the variation observed in plants, animals, and other organisms

9. A Summary of Mendel's Principles  Genes are passed from parents to their offspring.  If there are two or more alleles for a gene, some of the alleles may be dominant and others may be recessive.  In most sexually reproducing organisms, each adult has two copies of each gene. These genes are segregated from each other when gametes are formed.  The alleles for different genes usually segregate independently of one another

11.  Not all traits or dominant or recessive  Some traits are controlled by more than one gene or many alleles

12. Incomplete Dominance-  One allele is not completely dominant over the other  The heterozygous phenotype is b/w the two homozygous phenotypes  A cross between red (RR) and white (WW) four o’clock plants produces pink-colored flowers (RW).

13. Codominance-  both alleles contribute to the phenotype.  Heterozygous chickens are speckled with both black and white feathers. The black and white colors do not blend to form a new color, but appear separately.

14. Multiple Alleles-  Genes that are controlled by more than two alleles  more than two possible alleles can exist in a population

15. Coat color in rabbits is determined by a single gene that has at least four different alleles. C = full color; dominant to all other alleles

16.  c ch = chinchilla; partial defect in pigmentation; dominant to c h and c alleles

17.  c h = Himalayan; color in certain parts of the body; dominant to c allele

18.  c = albino; no color; recessive to all other alleles

19. Polygenic Traits-  Traits controlled by two or more genes  Skin, hair, & eye color in humans are polygenic traits controlled by more than four different genes

21.  Thomas Hunt Morgan used fruit flies to advance the study of genetics  Morgan and scientist tested Mendel’s principles and learned that they applied to other organisms as well as plants.

22.  Mendel’s principles can be used to study inheritance of human traits and to calculate the probability of certain traits appearing in the next generation

24.  Characteristics of any organism are determined by the interaction between genes and the environment. Ex: an individual has the gene to develop type 2 diabetes but their diet (environment) will determine if the will have it.