Questions and Answers
What is the primary function of the electron transport chain (ETC)?
Which component of the ETC is responsible for accepting electrons from NADH?
Which complex does NOT pump protons into the intermembrane space?
How many ATP are approximately produced from one molecule of FADH2 during the ETC?
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Which substance is an inhibitor of Complex IV in the ETC?
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What process describes the generation of ATP as protons flow back into the mitochondrial matrix?
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What role does cytochrome c serve in the electron transport chain?
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What is established as protons are pumped into the intermembrane space during the ETC?
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Which of the following compounds is an electron carrier in the ETC?
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What is the overall reaction product when molecular oxygen is reduced in the ETC?
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Study Notes
Electron Transport Chain (ETC)
Overview
- The electron transport chain (ETC) is a series of protein complexes located in the inner mitochondrial membrane.
- It is the final stage of cellular respiration, following glycolysis and the Krebs cycle.
Function
- The primary function of the ETC is to generate ATP through oxidative phosphorylation.
- It transfers electrons from NADH and FADH2 (produced in earlier stages of respiration) to molecular oxygen (O2), reducing it to water (H2O).
Components
-
Complex I (NADH dehydrogenase)
- Accepts electrons from NADH.
- Pumps protons (H+) into the intermembrane space.
-
Complex II (Succinate dehydrogenase)
- Accepts electrons from FADH2.
- Does not pump protons.
-
Complex III (Cytochrome bc1 complex)
- Transfers electrons from ubiquinone (Q) to cytochrome c.
- Pumps protons into the intermembrane space.
-
Complex IV (Cytochrome c oxidase)
- Accepts electrons from cytochrome c.
- Reduces oxygen to water.
- Pumps protons into the intermembrane space.
-
Ubiquinone (Coenzyme Q)
- Mobile electron carrier between Complexes I, II, and III.
-
Cytochrome c
- Mobile electron carrier between Complexes III and IV.
Proton Motive Force
- As protons are pumped into the intermembrane space, a proton gradient (proton motive force) is established.
- This gradient is used by ATP synthase to produce ATP from ADP and inorganic phosphate (Pi).
ATP Yield
- Roughly 2.5 ATP are produced per NADH and 1.5 ATP per FADH2 oxidized.
Inhibitors
- Certain compounds can inhibit the ETC, disrupting ATP production:
- Rotenone: Inhibits Complex I.
- Antimycin A: Inhibits Complex III.
- Cyanide: Inhibits Complex IV.
Importance
- The ETC is crucial for cellular energy production.
- It also plays a role in maintaining metabolic balance and regulating reactive oxygen species (ROS) production.
Key Concepts
- Oxidative phosphorylation: The process of ATP generation linked to the transfer of electrons through the ETC.
- Aerobic respiration: The dependence on oxygen in the electron transport process.
- Chemiosmosis: The process by which ATP is generated as protons flow back into the mitochondrial matrix through ATP synthase.
Overview
- The electron transport chain (ETC) is a collection of protein complexes situated in the inner mitochondrial membrane.
- Acts as the concluding phase of cellular respiration, following glycolysis and the Krebs cycle.
Function
- Main role is generating ATP via oxidative phosphorylation.
- Electrons from NADH and FADH2 are transferred to molecular oxygen (O2), resulting in water (H2O) formation.
Components
-
Complex I (NADH dehydrogenase):
- Accepts electrons from NADH and pumps protons (H+) into the intermembrane space.
-
Complex II (Succinate dehydrogenase):
- Accepts electrons from FADH2; does not contribute to proton pumping.
-
Complex III (Cytochrome bc1 complex):
- Transfers electrons from ubiquinone (Q) to cytochrome c while pumping protons into the intermembrane space.
-
Complex IV (Cytochrome c oxidase):
- Accepts electrons from cytochrome c, reduces O2 to water, and pumps protons into the intermembrane space.
-
Ubiquinone (Coenzyme Q):
- Functions as a mobile electron carrier linking Complexes I, II, and III.
-
Cytochrome c:
- Serves as a mobile electron carrier between Complexes III and IV.
Proton Motive Force
- Protons are pumped into the intermembrane space creating a proton gradient known as the proton motive force.
- This gradient is utilized by ATP synthase to convert ADP and inorganic phosphate (Pi) into ATP.
ATP Yield
- Approximately 2.5 ATP are generated for each NADH oxidized and 1.5 ATP per FADH2.
Inhibitors
- The function of the ETC can be inhibited by specific compounds:
- Rotenone: Blocks Complex I activity.
- Antimycin A: Inhibits Complex III.
- Cyanide: Disrupts Complex IV.
Importance
- The ETC is essential for efficient cellular energy production.
- It contributes to the maintenance of metabolic homeostasis and the regulation of reactive oxygen species (ROS) generation.
Key Concepts
- Oxidative phosphorylation: ATP synthesis linked with electron transfer through the ETC.
- Aerobic respiration: The process relies on the presence of oxygen for effective electron transport.
- Chemiosmosis: The mechanism through which ATP is formed as protons re-enter the mitochondrial matrix through ATP synthase.
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Description
This quiz explores the electron transport chain (ETC), the crucial stage in cellular respiration responsible for ATP generation through oxidative phosphorylation. Learn about the distinct protein complexes involved, their functions, and how they collectively transfer electrons to produce water. Prepare to test your understanding of this vital biochemical pathway.
