. Biological structure and function; proceedings. Biochemistry; Cytology. Cell Differentiation: A Problem in Selective Gene Activation Through Self-Produced Micro-Environ- mental Differences of Carbon Dioxide Tension \V. F. LooMis The Loomis Laboratory, Greenwich, Conn., It is an interesting fact that the subject matter of most of this sym- posium, DNA, RNA, ribosomes, mitochondria, etc., concerns the Uving cell as it was present on this earth a billion years ago, before Darwinian evolution even started. In those dark ages, before there were metazoa of any kind, the primary inventi
. Biological structure and function; proceedings. Biochemistry; Cytology. Cell Differentiation: A Problem in Selective Gene Activation Through Self-Produced Micro-Environ- mental Differences of Carbon Dioxide Tension \V. F. LooMis The Loomis Laboratory, Greenwich, Conn., It is an interesting fact that the subject matter of most of this sym- posium, DNA, RNA, ribosomes, mitochondria, etc., concerns the Uving cell as it was present on this earth a billion years ago, before Darwinian evolution even started. In those dark ages, before there were metazoa of any kind, the primary inventions of protein and nucleic acid. Fig. I. Relative sizes of a sulphur-bottomed whale- and the African elephant "Jumbo" (from Lull). -the largest living animal- synthesis were combined to etfect the miracle of replication. Once this had been achieved, a second series of inventions could begin, inventions by which replication could lead to differentiation and larger and larger multi- cellular organisms arise. InterceWuhr chemistry in other words is needed to explain how thirty quadrillion cells of about a hundred different types co-operate to make a sulphur-bottomed whale (Fig. i). Embryologically, of course, this vast number of cells is derived by clonal growth from a single fertilized ovum. Basically, the problem is one of selective gene activation. Since the nucleus of the fertilized egg contains all the genetic information needed to make each of the final differentiated cells present in the adult body, it is clear that only part of this information is used in any one cell. Take, for example, the insulin-secreting cells of the Islets of Langerhans. Sanger. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original IUB/IUBS International Symposium (1st : 1960 : Stockholm); International Union of Biochemistry;
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