The inhibitors of the electron-transport chain are substances that bind to some

Question

The inhibitors of the electron-transport chain are substances that bind to some of the components and block the passage of electrons at different points in the chain. This inhibition results in the accumulation of reduced forms before the inhibition point (where the inhibitor blocks the flow of electron), and oxidized forms of the components of the electron-transport chain behind the inhibition point. Recall that reduction is gain of electrons, whereas oxidation is loss of electrons. When a component of the electron-transport chain accepts an electron, it gets reduced, and when it transfers its electrons to an acceptor, it gets oxidized and the acceptor becomes reduced.

For example, in the following reaction coenzyme Q is in the oxidized form and accepts an electron to be in the reduced form. If we were to add a drug that blocks electron transfer at this step, coenzyme Q would remain oxidized, and FADH2 would remain reduced.

FADH2      +        CoQ      [Reduced form]      [Oxidized form]?       FAD         +     CoQH2[Oxidized form]     [Reduced form]

Identify the complexes and mobile electron carriers that remain reduced and oxidized due to the following blocker/inhibitors.

Explanation / Answer

2. CYTOCHROME C OXIDIZED AND MOLECULAR OXYGEN REDUCED DUE TO CYANIDE IN COMPLEX 4

3. CYTOCHROME C REDUCED AND QH2 AT Q0 SITE OXIDIZED DUE TO ANTIMYCIN IN COMPLEX 3

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