A closer look at the Electron Transport System 18. Describe the electron transpo

Question

A closer look at the Electron Transport System

18.  Describe the electron transport chain in the mitochondrial membrane by answering the following questions:

            a) What molecules drop off electrons onto the chain?

            b) Where did these molecules get their electrons that they drop off in the ETS?

            c) What do these molecules do after they have dropped of the electrons?

d) What happens to the electrons once they have entered the electron transport system?

            e) What molecule picks up the electrons at the end of the chain?

            f) What does that molecule become after it picks up the electrons?

Explanation / Answer

Electron transport occurs in the inner membrane of the mitochondrial matrix.

NADH + H+ and FADH2 are the molecules that drop electrons off in the ETS

These molecules get their electrons from reduced carbon compounds like carbohydrates (glucose), which are sequentially oxidized during glycolysis and krebs cycle

These molecules are recirculated or reused. Once they drop the electrons off, they become oxidized, and they go back to the biochemical pathways where they can be reduced again

Once the electrons enter into the electron transport chain, they are carried by a series of electron carriers (cytochromes). Each electron carrier has higher standard reduction potential than the electron carrier from which it accepts the electrons. Oxygen has highest standard reduction potential of all the members of ETC, and thus gets reduced, producing H2O

Oxygen, which has the highest standard reduction potential than all other carriers, picks up the electrons at the end of the chain

The molecule, after picking up the electrons, becomes H2O, or water

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