Where is the electron transport chain located?

In eukaryotes it sits in the inner mitochondrial membrane (cristae). Prokaryotes run an analogous chain in the plasma membrane. Glycolysis is cytosolic; the Krebs cycle is in the matrix; the ETC is in the membrane between them.

What is the final electron acceptor in the ETC?

Molecular oxygen. Complex IV transfers electrons to O₂ and, with protons from the matrix, produces water. That is why the chain stops without oxygen.

Does Complex II pump protons?

No. Succinate dehydrogenase (Complex II) feeds electrons into the Q pool but does not pump H⁺. Only Complexes I, III, and IV pump in the standard mitochondrial chain.

What is the difference between the ETC and oxidative phosphorylation?

The ETC is the electron-transfer and proton-pumping part. Oxidative phosphorylation is ETC plus ATP synthase using the proton gradient. Ask for oxidative phosphorylation when you want ATP synthase emphasized.

Is this the same as the photosynthetic electron transport chain?

No. Photosystem II / cytochrome b₆f / Photosystem I run in the thylakoid membrane and make NADPH. This page draws the mitochondrial respiratory chain that oxidizes NADH/FADH₂ and reduces O₂.

Can I make a labeled or blank ETC diagram, and is it accurate?

Yes. Describe a fully labeled inner-membrane map for learning, or ask for a blank worksheet to self-test, and the generator produces it. Because the diagrams are AI-generated illustrations, check complex order, NADH vs FADH₂ entry, and whether Complex II is shown as a non-pumping complex before you rely on them.

Biology Tool

Electron Transport Chain Diagram Generator Complexes I–IV

Generate a labeled ETC diagram with Complexes I–IV, Q, cytochrome c, and ATP synthase on the inner mitochondrial membrane.

NADH at I, FADH₂ at IIQ, cyt c, and O₂ → H₂OProton gradient and ATP synthaseLabeled or blank versions for revision

Electron Transport Chain Diagram Generator

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Electron Transport Chain Examples

Labeled, simplified, and blank mitochondrial ETC diagrams for study and teaching

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Simplified overview

A cleaner beginner version that keeps complex order, donors, and O₂ as the terminal acceptor.

simplifiedhigh-school

Proton gradient

Highlights that Complexes I, III, and IV pump protons, while Complex II does not.

protonschemiosmosis

Complete labeled ETC

The full inner-membrane map — NADH at I, FADH₂ at II, O₂ reduced at IV, protons returning through ATP synthase.

ETCcomplexeslabeled

Oxidative phosphorylation

ETC plus ATP synthase — the proton-motive force turning ADP and Pi into ATP in the matrix.

oxphosATPchemiosmosis

Cellular respiration context

Places the chain after glycolysis and the Krebs cycle, with NADH and FADH₂ feeding the membrane.

respirationmitochondriaoverview

Blank worksheet

The same membrane layout with names removed — fill complexes, carriers, and products from memory.

blankworksheet

What is the electron transport chain?

The mitochondrial electron transport chain (ETC) is a set of protein complexes in the inner membrane that take high-energy electrons from NADH and FADH₂ and pass them to oxygen. As electrons move, Complexes I, III, and IV pump protons into the intermembrane space. The resulting proton-motive force drives ATP synthase. This generator turns a description of that map into a labeled teaching figure. It is the respiratory chain, not the photosynthetic chain in thylakoids.

The complexes and carriers

Complex I (NADH dehydrogenase): NADH donates electrons to ubiquinone; 4 H⁺ pumped.
Complex II (succinate dehydrogenase): FADH₂ / succinate enter here; no protons pumped.
Ubiquinone (Q) carries electrons in the membrane to Complex III.
Complex III (cytochrome bc₁): Q-cycle; 4 H⁺ pumped; electrons to cytochrome c.
Cytochrome c is a mobile protein on the intermembrane-space face.
Complex IV (cytochrome c oxidase): electrons to O₂, making H₂O; 2 H⁺ pumped.
ATP synthase (Complex V) lets H⁺ return to the matrix and makes ATP.

NADH vs FADH₂

NADH feeds Complex I, so those electrons drive pumps at I, III, and IV (~10 H⁺ in the common teaching tally). FADH₂ skips Complex I and enters at II, so it only drives III and IV (~6 H⁺). That is why textbooks give a lower ATP yield for FADH₂. Ask the generator to keep that split visible when you want a study figure.

Labeled vs blank diagrams, and an honesty note

A fully labeled ETC is best when you are first learning the chain: every complex, carrier, donor, and O₂ as the terminal acceptor is named. A blank version of the same membrane layout is better for revision. This tool can produce both from a short description. These diagrams are AI-generated illustrations, so always check them against your textbook before relying on them. Membrane cartoons are easy to get wrong: Complex II must not pump protons, NADH should enter at I (not II), FADH₂ at II (not I), and this page is the mitochondrial chain, not photosystem II. Treat the output as a strong starting draft to verify, not an authoritative source.