Thermodynamic Rule Determining the Biological DNA Information Capacity
  A rigorous thermodynamic expression is derived for the total biological information capacity per unit length of a DNA molecule. The total information includes the usual four letter coding sequence information plus that excess information coding often erroneously referred to as "junk". We conclude that the currently understood human DNA code is about a hundred megabyte program written on a molecule with about a ten gigabyte memory. By far, most of the programing code is not presently understood. 
A. Widom, J. Swain, Y.N. Srivastava, S. Sivasubramanian, V.I. Valenzi
physics.gen-ph