The primacy of DNA in influencing and regulating biological behavior and evolution is based upon an unfounded assumption. A seminal article by H. F. Nijhout (BioEssays 1990, 12 (9):441-446) describes how concepts concerning genetic "controls" and "programs" were originally conceived as metaphors to help define and direct avenues of research. Widespread repetition of this compelling hypothesis over fifty years has resulted in the "metaphor of the model" becoming the "truth of the mechanism," in spite of the absence of substantiative supporting evidence. Since the assumption emphasizes the genetic program as the "top rung" on the biological control ladder, genes have acquired the status of causal agents in eliciting biological expression and behavior (e.g., genes causing cancer, alcoholism, even criminality).

The notion that the nucleus and its genes are the "brain" of the cell is an untenable and illogical hypothesis. If the brain is removed from an animal, disruption of physiologic integration would immediately lead to the organism's death. If the nucleus truly represented the brain of the cell, then removal of the nucleus would result in the cessation of cell functions and immediate cell death. However, experimentally enucleated cells may survive for two or more months with out genes, and yet are capable of effecting complex responses to environmental and cytoplasmic stimuli (Lipton, et al., Differentiation 1991, 46:117-133). Logic reveals that the nucleus can not be the brain of the cell!

Studies on cloned human cells led me to the awareness that the cell’s plasmalemma, commonly referred to as the cell membrane, represents the cell’s "brain." Cell membranes, the first biological organelle to appear in evolution, are the only organelle common to every living organism. Cell membranes compartmentalize the cytoplasm, separating it from the vagaries of the external environment. In its barrier capacity, the membrane enables the cell to maintain tight "control" over the cytoplasmic environment, a necessity in carrying out biological reactions. Cell membranes are so thin that they can only be observed using the electron microscope. Consequently, the existence and universal expression of the membrane structure was only clearly established around 1950.

In electron micrographs, the cell membrane appears as a vanishingly thin (<10nm), tri-layered (black-white-black) "skin" enveloping the cell. The fundamental structural simplicity of the cell membrane, which is identical for all biological organisms, beguiled cell biologists. For most of the last fifty years, the membrane was perceived as a "passive," semi-permeable barrier, resembling a breathable "plastic wrap," whose function was to simply contain the cytoplasm.

The membrane’s layered appearance reflects the organization of its phospholipid building blocks. These lollipop-shaped molecules are amphipathic, they possess both a globular polar phosphate head (Figure A) and two stick-like non-polar legs (Figure B). When shaken in solution, the phospholipids self-assemble into a stabilizing crystalline bilayer (Figure C).