1.In the organism there is a pair of factors that controls the appearance of a given characteristic. (We call them genes.)
2.The organism inherits these factors from its parents, one from each.
3.Each is transmitted from generation to generation as a discrete, unchanging unit. (The wrinkled seeds in the F2 generation were no less wrinkled than those in the P generation although they had passed through the round-seeded F1 generation.)
4.When the gametes are formed, the factors separate and are distributed as units
 to each gamete. This statement is often called Mendel's rule of segregation.
5.If an organism has two unlike factors (we call them alleles) for a characteristic, one may be expressed to the total exclusion of the other (dominant vs recessive).