Figure 2

Accounting for Mendel's observation of a 3(dominant):1(recessive) trait ratio in his F2 populations of plants. Mendel's notations for a dominant trait, a hybrid and a recessive trait were (A), (Aa) and (a) respectively. For reasons given in the preceding paper [1], a hybrid trait is represented in Figure 2 by (H). The molecular components of all traits are synthesised by a metabolic pathway. When the activity of any one enzyme in a metabolic pathway is changed in discrete steps, the flux to a trait component responds in non-linear (non-additive) fashion [3]. If the flux response is quasi-hyperbolic, as shown here, the hybrid trait (H) will be indistinguishable from the trait (A) expressed in the wild-type cell or organism, even when the enzyme activity in the hybrid (H) has been reduced to 50% of the wild-type activity. Trait (a), will be distinguishable from both traits (A) and (H) only if the enzyme activity is further reduced to a sufficient extent. Under these circumstances the trait series (A + 2H + a) becomes (3A + a); Mendel's 3(dominant):1(recessive) trait ratio is accounted for without introducing arbitrary and inconsistent arguments [1].