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 FADH_2 would remain reduced. FADH_2 [Reduced form] + CoQ [Oxidized form] rightarrow FAD [Oxidized form] + CoQH_2 [Reduced form] Identify the complexes and mobile electron carriers that remain reduced and oxidized due to the following blocker/inhibitors. You can use the electron-transport chain labeled in to help answer this question.

Explanation / Answer

1. When amytal blocks the flow of electron to Coenzyme Q, electrons are deposited at Complex I. Hence the last component that gets reduced is Complex I. Since electron doesn't pass to Coenzyme Q, it remains in oxidized form.Hence

Last component component that can be reduced due to inhibitor/blocker - Complex I

Last component component that remains oxidized due to inhibitor/blocker - Coenzyme Q

2:

When cyanide blocks the flow of electron to oxygen/complex IV, electrons are deposited at Cytochrome C. Hence the last component that gets reduced is Cytochrome C. Since electron doesn't pass to oxygen/complex IV, it remains in oxidized form.Hence

Last component component that can be reduced due to inhibitor/blocker - Cytochrome C

Last component component that remains oxidized due to inhibitor/blocker - complex IV

3:

When actinomycin blocks the flow of electron to Cytochrome C, electrons are deposited at Complex III. Hence the last component that gets reduced is Complex III. Since electron doesn't pass to Cytochrome C, it remains in oxidized form.Hence

Last component component that can be reduced due to inhibitor/blocker - Complex III

Last component component that remains oxidized due to inhibitor/blocker - Cytochrome C

4: Similarly

Last component component that can be reduced due to inhibitor/blocker - Complex I

Last component component that remains oxidized due to inhibitor/blocker - Coenzyme Q

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