Cytochrome B actually contains two different heme groups. And the electron first moves on to one heme group, then a second Hen group, and then it ultimately ends up on Ubiquinone. So this is basically the fully oxidized version of coal enzyme Q, also known as Ubiquinone. And when it gains that electron, it is basically partially reduced into a molecule we call the semiquinone radical ion, which contains a negative charge. And we'll see why we formed that in just a moment. So let's summarize the first half cycle of the Q cycle.