The spatial distribution and the chain length distribution during the spread of the chromosome (for the case shown in Figure2). (Top row) The spatial distribution. The horizontal plane is the N × N grid. A bar in a grid room represents the number of ribozymes, Rep (red), Nsr (green), Npsr (magenta) and Asr (blue), and the chromosome (yellow) / the control (white), in a stacked form. A black cap on a bar represents that the grid room is occupied by a protocell and thus the RNA molecules are in the protocell (a sole cap means an “empty” protocell). At step 1 × 104 (the left panel), 10 grid rooms at the diagonal of the grid were each inoculated with an protocell containing 5 molecules of the ribozymes and the sense chain of the chromosome; 10 other rooms, also at the diagonal of the grid, were each inoculated with a protocell containing 5 molecules of the ribozymes and the control. The empty protocells at this step result from the spread of the 10 empty protocells inoculated at step 1 × 103 (not shown here). The middle panel shows the spatial distribution at step 8 × 104, and the right panel at step 2 × 106. (Bottom row) The chain-length distribution of RNA molecules. The steps for the left, middle and right panels correspond to those shown in the top row. In the middle panel, the numbers of monomers (25,775) and dimers (3,389) are not fully represented; in the right panel, the number of monomers (9,287) is not fully represented.