The Gene




"Gene" is a term that has been in use since 1909, not long after Mendel's pea plant experiments first established biological laws of heredity. The name "gene" denoted the idea of a seed-like, physical substance responsible for the transmission of heredity and its expression in organisms.

The concept developed further with the discovery of DNA. Genes came to correspond to locations on a chromosome, which is made up of many lengths of DNA. The revelation of DNA's base pair structure in 1953 (Watson & Crick) showed that it had the stability necessary to preserve heredity and the capacity to self-replicate needed to transmit it.

From 1953 to the mapping of the human genome or full set of genetic material 50 years later, the "gene" on which many new developments had been based, has come to be seen as a concept showing its age, some science historians have argued.

The inescapable if well-guarded conclusion implied by the thrust of the last 40 years of research in molecular biology is that the "secrets of life" are much more complex and confusing than first thought. Ever mounting evidence in the form of scientific findings, rather than clarifying the picture, have tended to further obscure it, revealing only new levels of a vast complexity ingrained over the course of our three billion years of evolution.

Gene therapy

The example of gene therapy illustrates some of the difficulties encountered by researchers. Since the advent of gene splicing in the 1970’s, as genetic engineering technology passed from military to medical research, gene therapy held the promise of new treatments for congenital or hereditary diseases. With certain maladies, like hemophilia, said to be due to a specific gene's function in the organism, it was hoped that recombinant DNA techniques, or gene splicing-- synthetically introducing new DNA--would enable the treatment of such diseases through the replacement of the genetic material involved. While some successes have been attained in this field, notably the in vitro creation of spliced genes for producing human insulin and EPO (a hormone), to date, no successful gene therapy has been developed to treat congenital disease in humans.

Instead of producing results that tend to confirm the guiding paradigm, genetic research has accumulated much evidence undermining the concept of a physical gene. While certain cases like the "insulin gene" are consistent with the single gene-single function concept, research has shown that they are the exception. Rather than a specific gene expressing a particular character, what has usually been found is that no single gene is in fact involved in a given expression (phenotype). Instead, gene function may correspond to DNA located throughout the chromosome.

Not only is no single gene usually responsible for a single function, but research also indicates that non-genetic (epigenetic) factors such as cellular dynamics may also play a role in development. Instead of genes as the "book of life" responsible for the faithful transmission of heredity, at best the genome may be more like an active participant, among others, in an organism's development. Gene function and stability then might be better understood as part of a dynamic process within a complex cellular system. In other words, the organism as a whole is both the result of and the preserver of genetic information.


Just as genetic engineering has foundered in the vastness of biological complexity, so the discovery of the sequence of nucleotides or biochemicals in the genome, which it was hoped would suffice for understanding an organism, has only helped reveal the limits of genetic control of an organism's development. If the genome may be said to be the raw data of an organism's developmental "program," where the "program" may be found or what constitutes it is still unknown.

One theory that attempts to improve on the conceptual paradigm suggests that the genetic contribution to expression may be due not so much to DNA location as to differences in DNA arrangement: how the strands are physically wound together in the chromosomes, rather than "gene" location at one end or another of the chromosome.

In as much as research findings have tended to conflict with their guiding conceptual basis in the field, genetic or bioengineering cannot really be called a full-fledged science, practiced with a full understanding of the processes involved. Instead, it uses a trial and error approach, usually erring, and carried out in the absence of a conceptual model supported by research.


     first published 2006