216 CHAPTER 11 Bionanotechnology under direct genetic control) and there is variability (to a degree that is only poorly characterized) in sequence and length of the polysaccharides found fulfilling the same function in comparable organisms. 11.2 SOME GENERAL CHARACTERISTICS OF BIOLOGICAL MOLECULES The energy contained in a given system can be divided into two categories: (i) the multitude of microscopic or thermal motions sufficiently characterized by the temper- ature; and (ii) the (usually small number of) macroscopic, highly correlated motions, whose existence turns the construction into a machine (a device). The total energy contained in the microscopic degrees of freedom may be far larger than those in the macroscopic ones, but nevertheless the microscopic energy can usually be suc- cessfully neglected in the analysis of a construction (in informational terms, the macrostates are remembered but the microstates are not). Biological molecules are constructions. Hence a statistical approach, in which the motions of an immense number of individual particles are subsumed into