 Second, is that RQ can be synthesized without any UQ within the organism by using tryptophan metabolites instead.In the case of the prokaryotic organism "P. rubrum", RQ seems to be synthesized by addition of an amine group to a pre-existing UQ; thus UQ needs to be present as a precursor before RQ can be made.Figure 1 uses ‘n’ to represent the number of isoprene units between various organisms.