Genetics as a Control System

Genetics is a science of information storage in living systems. But, DNA is just a complicated molecule (or the double stranded form is a dimer) until it is in the place where the coded information may be expressed.

Development and cell differentiation are the processes of converting a genetic code into the expression of the code -- the phenotype. Therefore, genetics also is a science of biological process control. Genetic information may code for a protein, but it also may code for molecular responses to its local environment -- differences in pH, concentration of water molecules, electronic "fields" created by other molecules, etc. These changes in molecular shape are part of the properties that function in regulation of other genes, or code for the structural ability of a chromosome to fold. They allow the information about proteins that is coded in triplets to become protein. A process is the "becoming" and the protein is the product.

The process is called "magic" until we begin to understand it, and then it becomes "science." This semester we will study the science of genetics.

The recent molecular details we have learned from the genomes that have been sequenced, and from the "genomics" revealed of how hundreds of sets of gene function together are creating a major revolution in our understanding of genes and phenotypes and environmental effects. Today we are realizing more than ever that we have large communities of genes that work together, and create the systems of a living organism. We can now begin to understand two important features that were only imagined only a decade or so ago:

1. There is a seamless continuity between the environmental conditions not coded in the genes and the environmental conditions for genes created by the actions of other genes in the community.

2. The genome is both highly integrated and interdependent, and also affected by the organization; neighbors affect the functions of neighbors, so there are "neighborhoods" within communities of genes.

That is, we now recognize the ecology of genomes and the ecology of organisms as a continuum.

Processes are Represented by Models

Genetic information is transmitted from generation to generation in gametes (processes of gametogenesis and fertilization), from cell to cell in nuclear division (process of mitosis), and from molecule to molecule in template-moderated polymerization (processes of DNA synthesis, RNA transcription, RNA translation into proteins, folding of nucleic acids and proteins mediated with "helper" molecules). The genetic information in a genome is insufficient to "make" an organism! It further must be translated into form and function of individual organisms (processes of biochemistry, physiology, and development). Therefore, often we study genetic processes indirectly. We construct models that explain the results, and hope that the models approximate the multitudes of biochemical, physiological, developmental, and environmental process that actually produce the results. Contrary to claims by non-scientists, particularly non-geneticists, as a result of recent studies of the genome and genomic function, we are much farther from understanding life than we realized before we knew these things!

Science constructs models to represent an approximation of the actual processes. The actual processes are too complicated to understand fully, so the models are only as good as we can make them, or as good as we need their approximation to be for some purpose. The models are a "story" about "How?" something happens.

Science is NOT about "Truth," but about Useful Approximations,

(maybe with a grain of truth)

definitely based on observations and usually tested by experimentation!

Very often we have not learned the "hows," but have substituted "just so stories" in the form of models. Testing and improving these models is the subject of current and future research. We don't have the relevant observations that document the way processes operate. However, we can logically supply a sketch of likely processes that will fill the gaps in our knowledge. If we are to think in terms of "processes" and "systems" we will have to insert temporary descriptions of missing steps, even if we say, "By a miracle we get from A to B."

I hope you enjoy this course, and catch the spirit of a perpetual quest for "how and why" in every aspect of genetics, indeed, in Life.