Biochemistry Study Set 13
Quiz 9 :
Proton motive force is the force generated when the protons are pumped from high concentration to low concentration. It is observed in the mitochondria. The inner mitochondrial membrane consists of low proton concentration as compared to outer membrane and thus drives the protons in the inner membrane. The transfer of protons across the membrane helps in running electron transport chain that is used for ATP (adenosine triphosphate) production.
An electron transport chain (ETC) is a series of complexes that transfer electrons from electron donors to electron acceptors via redox carriers, and couples this electron transfer with the proton pumping across the mitochondrial membrane. Mitochondrial inner membrane consists of five different complexes. The complexes of inner mitochondrial membrane are as follows: 1. Complex I: Proton Pump 2. Complex II: Succinate Dehydrogenase 3. Complex III: Loop Mechanism 4. Complex IV: Pump and Annhilation 5. Complex V: ATP Synthesis
The electron transport chain consists of five complexes; one of them is complex II (Succinate dehydrogenase). This succinate dehydrogenase is also a part of Krebs cycle. This same enzyme converts succinate to fumarate in Krebs cycle. Thus, the third last step of Krebs cycle involving conversion of succinate to fumarate is also a part of electron transport chain.