Electron Transport Chain: Mitochondrial ETC, Components and Inhibitors II With MCQ II Important for ICAR, ASRB-NET, GATE, IIT-JAM, GAT-B exams

By the process of Electron Transport System, a large amount of energy that is stored in the covalent bonds of Pyruvate is converted to ATP.

Cellular Respiration is an Aerobic process that requires Oxygen and involves conversion of Pyruvate to CO2 and H2O.

How is Energy transferred?

Compound/Molecules are made up of atoms and these atoms were linked together by bonds and the energy is stored in these bonds. Energy can be transferred by breaking or making of bonds. 

Cellular respiration basically involves transfer of energy from one compound to another.

Transfer of energy can be done by transfer of electrons.

This transfer of electrons is called as Oxidation and Reduction.

Loss of electrons is called as Oxidation and Gain of electrons is called as Reduction.

EXAMPLE: In glycolysis the glucose is oxidized to Pyruvate by losing its electrons.

Another method of energy transfer involves transfer of Hydrogen (H)

                                                            H   →  H+ and e-

So, energy can be transferred by transfer of hydrogen.

The more Reduced the molecule is, the more energy is stored in its covalent bonds.

ELECTRON TRANSPORT CHAIN:

It is a Respiratory chain that transfers electrons and releases energy.

LOCATION: Inner membrane of Mitochondria.

The transport of electrons occurs by some carrier proteins arranged in form of four protein complexes (I, II, III, and IV), it contains proteins and electron carriers.

Among these four protein complexes three are transmembrane and one is soluble one.

Ubiquinone is the mobile electron carrier.

NADH and FADH2 are electron carriers, these electron carriers undergo oxidation and other molecules get reduced. 

O2 is the molecule that eventually accepts these electrons and gets reduced to form H2O.

NADH →  NAD + + H + + 2 e

FADH2→ FAD + 2 H + + 2 e

During the Electron Transport Chain flow of electrons results in active transport of Protons from mitochondrial matrix to inner mitochondrial membrane, this will create a proton gradient means more concentration of protons on one side of membrane and lesser on other side.

The protons come back to mitochondrial matrix through a channel protein named ATP Synthase.

Components of Electron Transport Chain are:

NADH Dehydrogenase

Succinate Dehydrogenase

Cytochrome bc1 complex

Cytochrome oxidase

ATP synthase

Along with the above components some other components were:

ATP/ADP Translocon

Phosphate transferase

Uncouplers

ATP/ADP Translocon and Phosphate transferase together form Synthetosome

Uncouplers are the one that inhibits ATP synthase

QUESTION PRACTICE:

Components of the mitochondrial Electron Transport Chain (ETC): 

 A. NADH‐Coenzyme Q oxidoreductase 

 B. Cytochrome bc complex 1 

 C. Ubiquinone 

 D. Cytochrome C 

 E. Cytochrome C Oxidase 

Choose the correct sequence of electron transfer through the aforementioned components of the mitochondrial ETC

 1. A, B, C, D, E 

2. A, C, B, D, E 

3. A, D, B, C, E

4. A, B, D, C, E 

Which of the following inhibit are inhibitors of ETC (ICAR PG Animal Biotechnology 2020)

Rotenone

Amobarbital

Peircidin A

Chlorpromazine

Atractyloside

Choose the most appropriate answer

A, B, C, E

A, B, C, D

B, C, D, E

A, C, E

The following is the list for various inhibitors of respiratory chain (Column I) and their possible mode of action (Column II).

Match the correct choices from Column I with the choices given against Column II from the above table and select the correct answer from the matches given below:

1. A-I, B-II, C-III, D-IV 

2. A-II, B-III, C-IV, D-I

3. A-III, B-IV, C-II, D-I 

4. A-L, B-III, C-II, D-IV

Match List I with List II (ICAR PG Crop Science)

Choose the correct answer from the options given below:

A-II, B-III, C-IV, D-I

 A-I, B-II, C-IV, D-III 

A-III, B-II, C-IV, D-I 

A-IV B-III, C-I, D-II

The Process of Electron Transport System in Mitochondrial Matrix involve (ICAR UG)

A. NADH+H----> NAD (Complex I, NADH Dehydrogenase)

B. 1/2 O2 +2H----->H2O(Complex IV, Cytochrome c oxyase)

C. ComplexIII Cytochrome b

D. Succinate------>Fumarate ((Complex II, succinate Dehydrogenase)

E. ADP+P---->ATP

CHOOSE the correct answer from the given options :

A>C>D>E>B

A>B>D>C>E

A>D>C>B>E

A>B>C>E>D