The electron transport chain (ETC) is the final stage of aerobic respiration. It transfers energy-rich electrons through a series of carriers and uses some of that energy to move hydrogen ions across the inner mitochondrial membrane. This lesson explains how electrons enter and travel through the chain, and why oxygen is essential to the process.
In eukaryotic cells, multiple copies of the ETC are embedded in the inner mitochondrial membrane. In prokaryotes, the chain is found in the plasma membrane. The chain consists of four large protein complexes, numbered I through IV, along with mobile electron carriers.
All flashcards
What is the electron transport chain?
Membrane-associated carriers and protein complexes that pass electrons through redox reactions, ultimately to oxygen.
How do NADH and FADH2 enter the electron transport chain?
NADH donates electrons to Complex I; FADH2 donates them to Complex II and bypasses Complex I.
What roles do ubiquinone and cytochrome c play?
Ubiquinone carries electrons from Complexes I and II to III; cytochrome c carries them from III to IV.
What is chemiosmosis?
The use of energy stored in an ion electrochemical gradient to drive a cellular process.
What is oxidative phosphorylation?
Mitochondrial ATP production coupled to electron transport and chemiosmosis.
Quiz questions
What two differences together make up the mitochondrial electrochemical gradient?Answer: A difference in hydrogen-ion concentration and a difference in electrical charge.
How does chemiosmosis use an ion gradient?Answer: It uses the gradient's stored energy to drive a cellular process.
In mitochondria, which direction do hydrogen ions flow through ATP synthase during ATP production?Answer: From the intermembrane space into the matrix.
What distinguishes oxidative phosphorylation from photophosphorylation?Answer: Oxidative phosphorylation is linked to mitochondrial electron transport; photophosphorylation uses light-driven gradients.
Why can the ATP yield from glycolytic NADH vary among tissues?Answer: Different shuttles can transfer its electrons to carriers that enter the chain at different points.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.