"Nucleic acids"

Date:
1957
Reference:
PP/CRI/I/1/14
Catalogue details

Licence: In copyright

Credit: "Nucleic acids". Source: Wellcome Collection.

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    Jgffî** w * ' New polymers with tailored properties are continually being created to meet new needs, new markets. In the grafting of monomers to polymers, re search is being stimulated by the unusual degree of energy control possible with ionizing radiation from scanned electron beams. The Van de Graaff particle accelerator is a principal source of this controllable ionizing radiation. Powerful, efficient, and safe in operation — the Van de Graaff is exceptionally versatile. • It can irradiate liquids, gases, solids, powders, and sponges. • Processing can be handled in trays, pipes, rolls, sheets, or bottles. • The beam can be either scanned or concentrated. • Voltage and current can be controlled through a wide range, with dosage monitored automatically. Typical industrial applications in which the Van de Graaff is pro viding useful data are: cross-linking, sterilization, pasteurization, catalysis, radiation finishing, polymerization, vulcanization, and molecular grafting. Now available for your experimental and developmental program, the new radiation facility at our plant will enable you to learn what ionizing radiation may do for your product. Write us for details or request bulletin F describing this new facility which is offered for experiment or limited production on a time-rental b again we have a suggestive general theory but very few facts, although the ones we have are interesting enough. The theory says very simply that the nucleic acids control the making of each organism's characteristic living sub stances—its proteins. DNA bears the master plans, carrying them on from generation to generation; RNA consti tutes the working copies used in the actual synthesis of the proteins. This production is controlled in a rather straightforward way by the sequence of bases in each nucleic acid, which de termines in what particular order amino acids will be assembled in the polypep tide chains that make up a protein. The order is all-important, for it governs the character and functions of the protein. I think it very likely that this hypoth esis is correct, at least in broad outline. It makes sense of an enormous body of biochemical facts, and it has the beauty which we associate with simplicity and generality. Moreover it has been a pow erful guide in attacking the bewildering complexity of biological systems. Tet us consider first the function of ■*- J RNA. It is found mainly in combina tion with protein in particles in the cyto plasm of the cell. These particles are believed to contain the templates on which specific proteins are modeled. The most convincing evidence that RNA is responsible for the specific con struction of proteins has come from recent work on the tobacco mosaic virus, done mainly by Heinz Fraenkel-Conrat and his colleagues at the University of California and by Gerhard Schramm and co-workers at the University of Tübin gen in Germany. They have separated the RNA from the proteins of the virus and used the RNA, separately and in combination with different proteins, to generate virus progeny. RNA alone, in oculated into a tobacco plant, has proved capable of reproducing the virus. In this case the progeny multiplying in the in fected plant had the protein correspond ing to the virus strain from which the RNA was taken, although the plant had never seen this protein before. Equally remarkable is the fact that a mixed vi rus, made by combining the RNA of one strain with the protein of another, yields progeny which contain not the new protein but the protein with which the RNA was originally associated. In other words, the infected plant manu factures a protein dictated by the RNA, not a copy of the protein actually given to it. This result illustrates very well a hypothesis which my colleagues and I call the Central Dogma: namely, that
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