Wang, D. Biol Philos (2005) 20: 453. doi:10.1007/s10539-005-5584-6
How to interpret the “molecular gene” concept is discussed in this paper. I argue that the architecture of biological systems is hierarchical and multi-layered, exhibiting striking similarities to that of modern computers. Multiple layers exist between the genotype and system level property, the phenotype. This architectural complexity gives rise to the intrinsic complexity of the genotype-phenotype relationships. The notion of a gene being for a phenotypic trait or traits lacks adequate consideration of this complexity and has limitations in explaining the genotype-phenotype relationships. I explore ways toward an integrative interpretation of the gene in the context of multi-layered biological systems. A gene, I argue, should be interpreted as a functional unit that is responsible for the trans-generation passage of the capacity to dynamically produce a biochemical activity or biochemical activities. At the molecular level, a gene is a genetic unit, a stretch of DNA sequence, which dictates the behavior and the dynamic production of the encoded cellular component(s). Embedded in a gene’s quadruple DNA code are the regulatory signals, such as those for RNA splicing and/or editing, as well as for transcription factor binding. A regulatory signal can be recognized by the gene expression machinery in one state, but not in another. The confusion caused by RNA splicing, editing, and a gene’s selective tissue distribution pattern is addressed. Instead of a context-dependent definition of the gene, I argue for the view that it is the same gene displaying multiple meanings, subject to differential interpretation by the cellular machinery in different states. In other words, the same gene gives rise to different products and expression levels under different conditions.