Genetics

 

Evelyn F. Keller, The Century of the Gene, 2000.

 

The life of a powerful word

 

GENE

1900       de Vries

       Correns

       Tschermak

 

Independently, all of them ‘rediscovered’ Mendel’s work on the inheritance of peas

 

1906       genetics’ was coined as a term as “a new and well developed branch of physiology”

 

1909 “the term gene came along three years later, introduced by Wilhelm Johannsen.”

p.1

“free of the taint of preformationism" – such as Darwin’s gemmules

 

Weismann’s (chromosome discoverer) determinants

 

“many characteristics of the organism are specified in the gametes by means of special conditions, foundations, and determiners which are all present in unique, separate, and thereby independent ways–is short, precisely what we wish to call genes.”       

Keller. P. 2.

 

“useful as an expression of ‘unit factors.’ ‘elements’ or allelomorphs’ in the gametes, demonstrated by the modern Mendelian researches…as to the nature of the ‘genes,’ it is of yet no value to propose any hypothesis; but that the notion of the gene covers a reality is evident in Mendelism.”

 

1933              T. H. Morgan (fruit flies)

“as to what genes are–whether they are real or purely fictitious.”

 

“genes had become incontrovertibly real.”

 

“the biological analogue of the molecules and atoms of physical science, endowed with the properties that would make it possible ‘to explain by their combinations the phenomena of the living world.’”

pp. 2-3

 

H. J. Muller

They were “the fundamental unit of heredity” and “the basis of life.”

 

The key to the text’s purpose and schematice approach is page 3.  

 

“Just what sort of entity is a gene?

 

Perhaps it was some sort of chemical molecule, but of what sort?

 

“What is it made of, how big is it, and above all, from what comes its miraculous power to determine the properties of a developing organism and, at the same time, ensure the stability of those properties from one generation to another.”                  

p. 3

 

1943

Avery, Macleod, and McCarty’s identification of DNA – nucleic acid “as the carrier of biological specificity in bacteria.”

 

Beadle and Tatum

"The one gene-to one enzyme hypothesis” of Beadle and Tatum

 

1953       Watson and Crick (Franklin and Wilkins) “which convinced biologists not only that genes are real molecules but that they consisted of nothing more mysterious than deoxy…”

“became the foundational concept capable of unifying all of biology.”

 

“new era of analysis.”

p. 3.

The most dramatic advances in a century

p. 4

 

1970s recombinant DNA technology

 

1990s Human genome project

 

“promised to reveal the genetic blueprint that tells us who we are.”

 

Sequencing of bacteria, yeast and roundworm genomes preceded the HGP

p. 4

 

“2000 the genome of Drosphila” sequenced

p. 5

 

“misguided and misleading”?

“the ways in which t has transformed.” Our expectations.

 

“Contrary to all expectations, instead of lending support to the familiar notions of genetic determinism that have acquired so powerful grip on the popular imagination, these successes pose critical challenges to such notions.”

 

“in this new science of genomic, twentieth-century genetics has achieved its apotheosis. Yet its very successes that have so stirred our imaginations have also radically undermined their core driving concept, the concept of the gene.”

p. 5.

“the multitude of encoding regions in even a simple genome.”

p. 6.

“Spoke as if sequence information would, by itself. Provide all that was necessary for an understanding of biological function.”

p. 6

“Instead f a Rosetta Stone,’ molecular geneticist—suggests that ‘it might be more appropriate to liken the human genome sequence to the Phaestos palace…by in large we are functional illiterates.”

p.6

functional genomics rather than structural genomics—is heard with growing frequency.

p.7

“the sequence is” rather as a tool

p. 7

“For almost fifty years, we lulled ourselves into believing that that, in discovering the molecular basis of genetic information, we had found the ‘secret of life’; we were confident that if we could only decode the message in DNA’s sequence of nucleotides, we could understand the ‘program’ that makes an organism what it is.”

p. 7.

 

“how large the gap between genetic ‘information’ and biological meaning really is.”

p. 8

“marveling not at the simplicity of life’s secrets  but at their complexity.”

 

“These tools are themselves the direct product of the most recent advances in molecular genetics and genomics; yet at the same time, and in the most eloquent testimony to the prowess of science I can imagine, they have worked to erode many of the core assumptions on which these efforts were first premised.”

pp. 8-9.

 

“”the limitations of the most extreme forms of reductionism”

p. 9.

 

“the primacy of the gene as the core explanatory concept of biological structure and function is” eclipsed.

p. 9.

 

Shift in focus from the gene “To genetic, epigenetic, and ‘post-genomic’ metabolic networks, and even to multiple systems of inheritance.”

p. 9.

 

Including “numerous elements defying classification in the traditional categories of animate and inanimate.”

p. 10.

 

“despite all its ambiguity, it has not yet outlived its usefulness.”

p. 10.

Exists as an “operational; shorthand” for identifying specific “levers or handles” for effecting fundamental biological changes.

 

“in marketing the products of a rapidly expanding biotech industry.”

p. 10.

 

Evelyn Fox Keller, The Century of the Gene, 2000.

Science: the microcosm

.

 

Editorial note

 

The architecture of Phaistos is more simplified compared with Knossos, and it is built in an orderly arrangement that refers to a single architect. The building outlines and the ground plan is easily deciphered by the visitor at first glance, however further examination reveals the complexity built into the site over hundreds of years of destruction and rebuilding cycles. The complex of architectural elements is a delightful amalgam of the old and new palace structures. During the rebuilding of the palace in 1700 BC several of the rooms from the old palace were retained in the new building, and archaeologists today have excavated several areas of the new palace to reveal the older structures below. The pavement of the west courtyard along with the few bottom steps of the converging staircases have been exposed during modern excavations, for they were buried one meter deep when the new palace was built.

 

More on Phaistos Palace, in Crete.

 

 

Darwin

 

links