Chapter 10 Mendel’s Model

On the basis of the experiments and data collected by Mendel, he proposed a model for how traits are inherited in pea plants.

10.1 Mendel’s first law

Mendel’s first law or the law of equal segregation states: when a gamete is formed the members of a gene pair (alleles) separate so that each gamete receives only one copy.

10.2 Mendel’s second law

Mendel’s second law or, the principle of independent assortment states: different gene pairs assort independently in gamete formation

The key to understanding the relationship between the inheritance of discrete factors and the phenotypes is an understanding of chance, or probability.

10.3 Probability

The probability of a particular outcome may be considered equivalent to the number of times an outcome is expected to occur over a large number of repeated trials. When expressed as a ratio this is equivalent to the probability that the particular outcome will occur in a single trial.

10.3.1 Additive Law of Probability

Prob(A or B) = Prob(A) + Prob(B)

The probability of the realization of one or the other of two mutually exclusive possibilities, A or B, is the sum of their separate probabilities.

10.3.2 Multiplicative Law of Probability

Prob(A and B) = Prob(A) x Prob(B)

The probability of two independent possibilities, A and B, being realized simultaneously is given by the product of their separate probabilities