Published Papers

Molecular Architecture and the Processes of Life. May 28, 1948.

Page 06 [4]

< Previous Page     Page 05 [3]

Back to Document Index Molecular Architecture and the Processes of L...

Next Page > Page 07 [5]

Title:	Molecular Architecture and the Processes of Life [6 of 15]
Creator:	Pauling, Linus, 1901-
Publisher:	Nature.
Date:	1948-05-28
Subject:	Molecular structure
Description:	Nature, vol. 248. Original typescript.
Type:	Text
Format:	text/plain
Language:	en
Identifier:	jessebootlecture-pg06.jpg
Source:	Master scanned with Epson GT-10000+ flatbed scanner at 600 dpi.
Rights:	http://osulibrary.orst.edu/specialcollections/coll/pauling/dna/copyright.html
Full Text:	character of having short wings rather than long Nvings is clearly not a very simple one-it is not easily interpreted in terms of chemistry and of molecular structure. On the other hand, the colour of the eye might be easily inter- preted, inasmuch as the presence or absence of an enzyme capable of catalyzing the reaction of formation of a special pigment producing eye colour might determine the colour of the eye, and the corresponding chemical reaction would be catalyzed by a special enzyme. Accordingly the funda- mental nature of this character would be the presence or absence of this enzyme, and the basic property of the corresponding gene would be that of being able to cause the manufacture of this specific enzyme in the body. Beadle and his collaborators have carried out the investigation of hundreds of these chemical genes that are responsible for the production of hundreds of different specific enzymes, catalyzing different chemical reactions. The organism that they have used is the red bread mold, Neurospora. I may mention some examples of chemical characters'. One of our chemical senses is the sense of taste-the taste of a substance depends upon the structure of its molecules. There are two kinds of people with respect to ability- to taste a certain substance, phenylthiourea. This substance seems to some people to be very bitter, whereas to others it is quite tasteless. The inheritance of this character is determined by a single gene, transmitted by the pure Mendelian mechanism. Beadle has pointed out that it would be difficult to determine this character for a fruit fly, because of the difficulty of finding out whether the material seemed to be bitter or tasteless to this small animal. It is interesting in this connection to mention, however, that some investigators in Maryland thought that they would try to find out whether the substance was also either bitter or tasteless to rats, and they began a series of experiments with this in view. They discovered, instead, that the substance, while harmless to human beings, is very poisonous for rats, and, following up this line, they found that a closely related substance, a thiourea, is still more poisonous to rats. This substance is now finding extensive practical use as a rat poison. Another simple chemical gene in man is the one involved in the oxidation of phenylpyruvic acid. The chemical reaction of oxidizing this substance