Oxidative Phosphorylation

What is cellular respiration?

• Catabolic process in which organic molecules are broken down within the cells via the electron transport chain

• Carbohydrates, lipids and amino acids are catabolised in three stages of cellular respiration

• Resultant electrons are transferred to reduced cofactors NADH or FADH2

• In oxidative phosphorylation, the energy generated from NADH and FADH2 is utilised to produce ATP

What is chemiosmotic theory?

the coupling of ATP synthesis to the energy stored in an electrochemical proton gradient (rather than by direct chemical transfer of high energy groups)

How is chemiosmotic theory split into two parts?

Step 1: The electron transport chain uses electrons to pump protons across the membrane - proton motive force

Step 2: The proton gradient is then utilised by ATP synthase to drive the synthesis of ATP

What is Complex II?

• FAD accepts two electrons from succinate

• Electrons are passed, one at a time, via iron-sulfur centers to ubiquinone, which becomes reduced QH₂

• Does not transport protons

What are the two functional units of mitochondrial ATP synthase complex?

F₀

• integral membrane complex

• transports protons from IMS to the matrix, dissipating the proton gradient

• energy transferred to F₁ to catalyse phosphorylation of ADP

F₁

• soluble complex in the matrix

• catalyses ATP synthesis

What does uncoupling ATP from ETC generate?

ATP