On the Regulation of Gene Activity

According to modern concepts, the deoxynucleotide sequence which constitutes a gene participates in two distinct chemical processes. In the first, for which the term replication should be reserved, free deoxyribonucleotides are linearly assembled by specific base-pairings, forming an identical sequence or replica of the original sequence; the second process, which we shall call transcription, allows the gene to perform its physiological function, i.e., to specify the molecular structure of a certain protein or polypeptide chain. Transcription does not appear to be a direct process, since it most probably involves the formation of an intermediate as carrier of the genetic information. Two stages may then be distinguished in transcription, the first of which is presumably closely similar to replication, involving, however, ribonucleotides instead of deoxynucleotides, and resulting in an RNA "transcript" of the original DNA sequence. In the second transcription stage, the RNA transcript in turn directs the assembly of...