VIDEO
HIGHLIGHT
Log InSign up
Electron Transport Chain | HHMI BioInteractive Video
SummaryTranscriptChat

Electron Transport Chain | HHMI BioInteractive Video

The Electron Transport Chain

This section provides an overview of the electron transport chain and its role in cellular respiration.

The Inner Mitochondrial Membrane and Enzymes (0:00:00 - 0:01:21)

  • The center of activity in cells is the mitochondria organelle, specifically the inner mitochondrial membrane.
  • Enzymes on the inner mitochondrial membrane catalyze the chemical reactions of respiration, including the electron transport chain.
  • Enzyme complex 1 is responsible for the first step of the electron transport chain, receiving electrons from coenzyme NADH produced by the citric acid cycle.
  • Coenzyme NADH is oxidized at one end of enzyme complex 1, releasing two electrons that hop to coenzyme Q, which becomes reduced.
  • Coenzyme Q carries electrons to the next step in the electron transport chain while traveling among membrane lipids.
  • The movement of charged electrons through complex 1 causes it to bend and transmit energy for pumping four protons across the membrane.

Enzyme Complex 3 and Oxygen Capture (0:01:43 - 0:03:31)

  • Enzyme complex 3 performs the second step of the electron transport chain by separating electrons from coenzyme Q and passing one electron to cytochrome c, which becomes reduced.
  • A complete reaction cycle of enzyme complex 3 transports four protons across the membrane.
  • Reduced cytochrome c carries electrons to enzyme complex four, which serves as a destination for electron transport.
  • In enzyme complex four, reduced cytochrome c delivers electrons to its reaction center where a molecule of oxygen is captured, split, and reduced.
  • The separated oxygen atoms accept electrons and pick up protons, resulting in two molecules of water.

Multiple Sources of Electrons (0:03:31 - 0:04:03)

  • Coenzyme NADH, a product of the citric acid cycle, provides electrons to enzyme complex 1.
  • Enzyme complex 2 catalyzes the oxidation of succinate in step 6 of the citric acid cycle, releasing two electrons that hop to coenzyme Q.

The transcript is already in English.

Video description

This animation shows how the enzyme complexes of the electron transport chain harvest energy from cofactor molecules to pump protons across the mitochondrial membrane and establish a chemical gradient. It is the fourth of six animations about cellular respiration. To view the rest of this series on cellular respiration, go to the full playlist at: https://www.youtube.com/playlist?list=PLI1XjFOSo4gOymAvlRs_8sSUH1BKKUiDA To view a specific part of the series, use the following links: Part 1: Glycolysis https://youtu.be/BO0zL03CtDs Part 2: Pyruvate Dehydrogenase https://youtu.be/rSPUYA3gWK8 Part 3: Citric Acid Cycle https://youtu.be/IlSFn0gRyC4 Part 4: Electron Transport Chain https://youtu.be/zNpeuA4gtq0 Part 5: ATP Synthase https://youtu.be/CSrtewCJbpg Part 6: ATP in Use https://youtu.be/vUC5njkOq7o For more information and related materials for this animation, visit HHMI BioInteractive: https://www.biointeractive.org/classroom-resources/electron-transport-chain