Biomedical Engineering Reference
In-Depth Information
Today, fifteen years later, a series of genomes have been mapped
through massively funded, international, industry-government-
university-philanthropy consortia. Many consequences and questions
follow from this achievement. Among them, there needs to be a rethink-
ing of what a gene is, because scientifically speaking genes are not what
they used to be. Brenner ruefully remarks: “Old geneticists knew what
they were talking about when they used the term 'gene,' but it seems to
have been corrupted by modern genomics to mean any piece of expressed
sequence.” Instead of the misleading and anachronistic term gene,
Brenner proposes to substitute the phrase “genetic locus” to indicate
“either an open reading frame or a site to map mutations.” An open
reading frame is “a DNA sequence that potentially can be translated into
protein.” Brenner continues, “As proteins are the workhorses of organ-
isms, an approach from the sequences that tells you in a mechanical
fashion what the amino acids are in each protein is infinitely more eco-
nomical than purifying and analyzing the vast number of proteins. The
genes can then be cloned and studied, often through mutation.”
9
It
should come as no surprise to learn that proteomics companies are
appearing, and calls for inventories of proteins are increasingly men-
tioned as vital.
Once the genomes are mapped and sequenced, and once the basic pro-
teomic cataloging work is accomplished, the functional biology will only
just have begun. Brenner observes that these maps are static. None of
the information in them as it is currently collected tells us when genes
are switched on and off, and for how long. Such information, Brenner
notes, is “absolutely essential . . . because in complex organisms, evolu-
tion does not proceed by enlarging the protein inventory but by modu-
lating the expression of genes.”
10
Thus, our understanding of the genome stands clearly in a period of
transition from so-called classical genetics to modern genomics and pro-
teomics, from expecting a thing to deciphering a function. Further, all
that rested on that classical expectation stands in need of reassessment,
even the assumed genetic gulf separating Drosophila from Homo sapiens;
hence the questions facing this volume. While there is perhaps room for
metaphysicians and ethicists to worry about the larger consequences of
such surprises, an equally serious concern is with the state of the science
that brought about this transformation and that promises more.
