From experimental clues to theoretical modeling: Evolution associated with the membrane-takeover at an early stage of life
Fig 5
The alteration of membrane contents with the rising of a ribozyme favoring phospholipid-synthesis (i.e., GR).
For each of the two subfigures, the upper panel shows the trend of relevant protocells while the lower panel demonstrates the trend of RPM (the ratio of phospholipids in the membrane) for these protocells (averaged for each type of protocell). Legends: C — empty protocells; Cgr — protocells containing GR; Cnr — protocells containing NR; Cnrgr — protocells containing NR and GR. RPM for a protocell is calculated as 2 × pnum/(2 × pnum + fnum), where pnum and fnum denote the number of phospholipids and that of fatty acids on the membrane respectively (note that a phospholipid molecule has two non-polar tails whereas a fatty acid has one). Here the vertical axis represents the average RPM of the corresponding protocells, and it is set to 0 ad hoc at the points where that kind of protocells does not exist. (a) The change of membrane contents during the spread of GR in empty protocells (the case is the same as the one shown in Fig 2a, but the horizontal axis adopts a smaller scale). (b) The change of membrane contents during the spread of GR in NR protocells (the case is the same as the one shown in Fig 2b).