Question

Which one is the last electron acceptor over ETC in oxidative phosphorylation?
(a) ${ H }_{ 2 }$
(b) ${ { Cyt }{ a }_{ 3 } }$
(c) ${ { Cyt }{ b } }$
(d) ${ CO }_{ 2 }$

Answer 1

Hint: They are the protein complex that undergoes the reduction- oxidation process and consists of a central iron atom having heme A in its molecule and are the fourth complex of the electron transport chain.

Complete step by step answer:
The ${ { Cyt }{ a }_{ 3 } }$ is the last acceptor of the oxidative phosphorylation that occurs in it. The oxygen is lastly accepted by the cytochrome protein belonging to the ${ { a }_{ 3 } }$ group. The cytochromes are of different types depending upon their binding sites and the type of heme present.
Additional information
- The Electron transport chain is a series of complexes that help in the transport of electrons from the donor to the acceptor of the electron by the process of reduction and oxidation.
- The ETSC consists of the enzymes, proteins, cofactors, and other substances.
- It is an exergonic process as the transport of electrons will form an electrochemical concentration gradient radiating the ATP in the form of energy.
- The ETC chain is found in the inner membrane of the mitochondria, consisting of the four complexes.
- The complexes are:
 (a) Complex I - NADH dehydrogenase, NADH ubiquinone oxidoreductase, and mitochondrial complex I.
 (b) Complex II - Succinate dehydrogenase or reductase.
 (c) Complex III - Cytochromes ${ { Cyt }{ bc}_{ 1} }$ complex and cytochrome c reductase.
 (d) Complex IV - Cytochrome c oxidase, and ${ { Cyt }{ a }_{ 3 } }$.
So, the correct answer is ‘${ { Cyt }{ a }_{ 3 } }$’.

Note: In 1894 - 1984 the process of oxidative phosphorylation was first discovered by Vladimir Engelhardt. In 1884 the cytochromes were first discovered as respiratory pigments by MacMunn but later in 1920 these cytochromes were rediscovered by Keilin and he named these pigments as cellular pigments or cytochromes.