When Watson and Crick proposed their three-dimensional double-helix DNA model in 1953, implications for the coding and replication of genetic information could not be experimentally verified. The concept of the gene and gene-expressed products gradually attained a concrete form. By 1978, it had become clear how to combine multicellular organism genes or genetic fragments with those of viruses, fungi, and bacteria to yield new metabolic instructions for producing novel products; scientists were then ready to apply those methods to exploit new technologies. The success of biomolecular procedures is based upon several related, but independent, developments:
1. The ability to clone genetic information (i.e., to isolate a selected segment and accurately reproduce it in large amounts).