At the end, we form a Ubiquinol because that semiquinol radical ion that is formed in the first half cycle picks up a second electron, is able to abstract two protons from the matrix of the mitochondria and form regenerate that Ubiquinol molecule. And that ubiquinol can then be used by this pathway here to basically generate the reduced cytochrome C. So we conclude the following four important points, and I've only listed three. So the first important point is the following. 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.