SEARCH Articles Figures Tables Q Cycle. The two electrons of a bound QH2 are transferred, one to cytochrome c and the other to a bound Q to form the semiquinone Q The newly formed Q dissociates and is replaced by a second QH2, which also gives up its electrons, one to a second molecule of cytochrome c and the other to reduce Q to QH2. This second electron transfer results in the uptake of two protons from the matrix. Prosthetic groups are shown in their oxidized forms in blue and in their reduced forms in red. [Publishers Imprint]