This lesson introduces the electron transport chain (ETC), explains how redox reactions release usable energy, and shows how that energy establishes a proton gradient.
An electron transport chain is a series of proteins and other molecules that pass electrons from electron donors to electron acceptors. The transfers occur through redox reactions: oxidation is the loss of electrons, while reduction is their gain. Because an electron lost by one molecule is gained by another, oxidation and reduction occur together.
All flashcards
What is an electron transport chain?
A series of proteins and other molecules that transfer electrons from donors to acceptors through redox reactions.
What happens to the donor and acceptor in a redox reaction?
The donor loses electrons and is oxidized; the acceptor gains electrons and is reduced.
What is the proton-motive force?
The electrochemical potential energy stored in a proton gradient across a membrane.
What is uncoupling in oxidative phosphorylation?
Protons return to the matrix without passing through ATP synthase, releasing gradient energy as heat.
What is reverse electron flow?
Electron transfer through electron-transport components in the reverse direction, driven by a strong proton-motive force.
Quiz questions
In the mitochondrial respiratory chain, where do electrons from NADH enter?Answer: At Complex I.
Which feature distinguishes Complex II from Complex I in the mitochondrial respiratory chain?Answer: It transfers succinate-derived electrons to coenzyme Q without pumping protons.
What is coenzyme Q's role in the mitochondrial electron transport chain?Answer: It is a lipid-soluble mobile carrier that transfers electrons to Complex III.
What is the outcome of electron transfer at Complex IV during aerobic respiration?Answer: Oxygen accepts electrons and is reduced to water.
How does proton flow through ATP synthase contribute to ATP production?Answer: It turns the rotor, changing catalytic-site conformations in the F₁ portion.