Question

Mitochondrial electron transport chain is
a. Cyclic phosphorylation
b. Oxidative phosphorylation.
c. Noncyclic phosphorylation
d. Photooxidation

Answer 1

Hint: Electron transport chain is the series of the protein complex and other organic molecules, arranged in series, where the energy produced in these complexes form the proton gradient through the redox reactions, and this is finally used to form the ATP.

Complete answer:
- The electron transport chain is embedded in the inner mitochondrial membrane. It consists of four complexes that are named as complex I, II, III, IV are present and along with them, 2 electron transporters are present, they are ubiquinone and cytochrome c.
- The majority of the electrons of the electron transport chain are given by NADH and FADH2 molecules, so after giving they are reduced to NAD and FAD where again participate in cycles of aerobic respiration and keep the cycles continuing.
- The electrons given by those molecules enter the complex I and the energy from this are utilized to the hydrogen ions from the mitochondrial matrix to inner membrane space and through the redox reactions, these electrons are transferred to the complex II, but this complex has less energy to pump the protons
- Later the electrons move from the complex II to complex III with the help of electron transporter ubiquinone and the energy produced here is utilized to pump the hydrogen ions from the matrix to space.
- With the help of cytochrome c, electrons are transported to complex IV where the same thing happens.
- The complex IV carries the electrons to oxygen molecules and these molecules split into oxygen atoms and accept the hydrogen ions and produce the water molecules and ATP.

Hence, the correct answer is option (B).

Note: Here in the electron transport chain the ATP is formed because of the transfer of electrons from NADH and FADH molecules to oxygen molecules by series of electron carriers, Hence this phosphorylation is termed as oxidative phosphorylation.