A mobile component within the electron transport chain is_____________?
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Answer: C. Ubiquinone
Explanation
Ubiquinone is a lipid-soluble, small molecule that diffuses freely within the inner mitochondrial membrane. It shuttles electrons directly between fixed protein complexes within the electron transport chain. This high mobility makes ubiquinone an essential electron and proton carrier in cellular respiration. Cellular respiration generates ATP through oxidative phosphorylation in the inner mitochondrial membrane. Ubiquinone is also widely known as coenzyme Q in biochemical and physiological literature. Mobile carriers are necessary to bridge the distance between large multi-subunit respiratory complexes.
Mitochondrial energy production supports cellular metabolism in high energy tissues like the heart and brain. Coenzyme Q supplements are studied for their role in supporting cellular energy metabolism and antioxidant defense. Deficiencies in mitochondrial electron carriers can lead to severe muscular and neurological disorders. Option A represents flavoproteins, which are typically tightly bound prosthetic groups within enzyme complexes. Option B represents cytochrome c1, which is a fixed component of the cytochrome c reductase complex. Option D represents cytochrome a, which forms a stationary part of the cytochrome c oxidase complex.
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