Derived from https://commons.wikimedia.org/wiki/File:ELLIPTICAL_GENETIC_CODE_Ian.png/File:Hydropathy_Molar_Volume_Genetic_Code_2.png A codon position is biased if the elliptical trace is: 1) not centered on the center of the (square) graph frame, and / or 2) contains a smaller-than-random volume. First position - dashed. Second position - solid. The strongest components (bias) for the encoding of anino acid residues are, in order: C in 2nd position = small size, medium hydropathy U in 2nd position = average size, hydrophobic A in 2nd position = average size, hydrophilic U in 1st position = not hydrophilic The y-axis is accurate (cubic Angstroms), but the x-axis could have some error from estimates of hydropathy. Redrawn from Figure 4 in http://www.complexity.org.au/ci/vol01/fullen01/html/ archive copy at the Wayback Machinewhich attributes the graph to Yang, M. M., W. J. Coleman and D. C. Youvan. 1990. In Reaction Centers of Photosynthetic Bacteria. M.-E. Michel-Beyerle. (Ed.) (Springer-Verlag, Germany) p209-218; listed by Google at [1] Date 30 May 2008 Source doug youvan Author Doug Youvan