MODULE 11: Chapter 11.1 Flashcards
What is the chemiosmotic theory?
ATP synthesis in mitochondria is accomplished by establishing a proton (H⁺) gradient across the mitochondrial inner membrane
What is chemiosmosis?
The movement of protons across the membrane down their concentration gradient to generate ATP
How is the proton gradient established in mitochondria?
By the outward pumping of H⁺ from the mitochondrial matrix by three large protein complexes powered by redox energy
What role does ATP synthase play in ATP synthesis?
ATP synthesis is accomplished by the inward flow of H⁺ through the membrane-bound ATP synthase complex
How do plant chloroplasts generate ATP?
By utilizing sunlight energy to establish an H⁺ gradient across the thylakoid membrane
What is the net result of the electron transport system?
The coupled oxidation of NADH and FADH2 with the reduction of molecular oxygen to form NAD⁺ and H2O
What are the reduction potentials of the NAD⁺/NADH and O2/H2O redox pairs?
NAD⁺/NADH (E°′ = −0.32 V) and O2/H2O (E°′ = +0.82 V)
What is the basic idea of chemiosmosis?
Energy from redox reactions is coupled to electron transfer in membrane-bound proteins that translocate protons across the membrane
What does the proton circuit in chemiosmosis behave like?
An electrical circuit
What is the role of uncouplers in the proton circuit?
They allow H⁺ to leak across the membrane without producing ATP, converting redox energy to heat
What happens if ATP synthase complex activity is inhibited?
Proton flow shuts down, oxidative phosphorylation cannot occur, leading to cell death
What are the primary structural features of a mitochondrion?
Outer mitochondrial membrane, intermembrane space, inner mitochondrial membrane (highly invaginated), mitochondrial matrix
How does the number of mitochondria per cell vary?
It depends on the energy requirements of the cell; slow-twitch muscles have more mitochondria than fast-twitch muscles
What is the estimated total surface area of the inner mitochondrial membrane in an average-sized human?
185,000 m²
How many copies of mitochondrial DNA does each mitochondrion contain?
5–10 copies
What are the five protein complexes required for oxidative phosphorylation?
- Complex I: NADH–ubiquinone oxidoreductase (NADH dehydrogenase) * Complex II: Succinate dehydrogenase * Complex III: Ubiquinone–cytochrome c oxidoreductase * Complex IV: Cytochrome c oxidase * ATP synthase complex
What is the function of coenzyme Q and cytochrome c in the electron transport system?
They are mobile electron carriers that transfer electrons between various complexes
How many protons are translocated out of the mitochondrial matrix starting with NADH oxidation?
10 H⁺
What is the stoichiometry of proton translocation back into the mitochondrial matrix for ATP synthesis?
3 H⁺ per ATP and 1 H⁺ per Pi
Fill in the blank: The proton gradient is a source of _______ energy.
electrochemical
True or False: Mitochondria are inherited only from the male sperm.
False
How many H⁺ are translocated per FADH2 that is oxidized?
6 H⁺
FADH2 bypasses complex I
How many H⁺ are needed for every ATP synthesized?
4 H⁺
3 H⁺ per ATP and 1 H⁺ per Pi
What is the role of ATP/ADP translocase?
Exchanges ATP for ADP
Essential to maintaining flux through the oxidative phosphorylation pathway
