The ubiquinone can actually carry two electrons, while the cytochromac can only carry a single electron. And that's exactly why we need this second pathway here to basically recycle the electron so that we can regenerate those Ubiquinol molecules and reuse the ubiquinol molecules in this above pathway. So we need this bottom step. So we see that in a single Q cycle, two Ubiquinol molecules are oxidized into ubiquinole, releasing four H plus ions to the inter membrane space. Two are released in this first process, and two are released in the second process. At the same exact time, a single quinone, or ubiquinone, is reduced into ubiquinone.