APPARATUS AND COMPUTER SOFTWARE FOR ANALYZING THE STRUCTURE OF BIOLOGICAL MATERIALS IN THE NATURE OF DNA, RNA OR PROTEINS, BY MEASURING THE MELTING TEMPERATURE OF AND THE RADIATION ABSORPTION BY THE BIOLOGICAL MATERIALS, NAMELY, ULTRAVIOLET AND VISIBLE SPECTROPHOTOMETERS, TEMPERATURE CONTROLLERS FOR PHOTOMETERS AND LABORATORY DEVICES, NAMELY, CELL HOLDERS FOR RADIATION-TRANSMISSIVE CELLS AND CUVETTES