The idea that membrane topology is a solid hereditary unit emerged from the original studies of protein topogenesis and was crystallized by Günther Blobel's phrase "omnis membrane e membrane" (PNAS, 1980, 77(3): 1245-12477.
Gregor Mendel, an Austrian monk, proposes that discrete, hereditary units he calls factors are passed down along family lines to produce recognizable traits.
In the early 1980s, Leroy Hood, a biologist at the California Institute of Technology, proposed to make the first automated DNA sequencer, which he pitched to the National Institutes of Health as a way to rapidly identify the billions of hereditary units in every human cell.
Plasmids are hereditary units physically separate from the chromosomes of the cell.
Sutton developed this hypothesis in "The Chromosomes in Heredity" (1903) and concluded that chromosomes contain hereditary units and that their behaviour during meiosis is random.
From the precise mathematical 3 1 ratio (of which he found several other examples), he deduced not only the existence of discrete hereditary units (genes) but also that the units were present in pairs in the pea plant and that the pairs separated during gamete formation.
For instance, Garrod's work on biochemical disorders and Sutton and Bovery's theory on chromosomes as the carriers of hereditary units (later confirmed by Bridges), must appear upfront following the discovery of Mendelian principles because they bolstered Bateson's advocacy of Mendelism to support the Darwin-Wallace theory.
Gregor Mendel's finding that hereditary units could be associated with particular observable traits and that in diploid organisms the apparent contribution from the two parents to a trait could be highly asymmetrical [1], led to the concepts additive and dominant (nonadditive) gene actions as well as the closely associated term recessive gene action.
For example, the understanding of chromosomes as discrete entities and the theories generated about them as hereditary units were constitutively tied up with counting techniques that 'immobilized, separated and enhanced them' (p. 248).
