Question

The chemiosmotic theory of ATP synthesis taking place in the mitochondrion is based on:
a. $Ca^{+}$ gradient
b. $K^{+}$ gradient
c. $H^{+}$ gradient
d. $Na^{+}$ gradient

Answer 1

The prime function of the mitochondria is the production of energy from the food we take. It is the “powerhouse” of the cell which produces energy in the form of ATP molecules. It is also involved in carrying out cellular metabolism.

Complete answer:
The mitochondria are membrane bound organelle present in the cell, which is responsible for energy production in the form of ATP. Apart from ATP synthesis, mitochondria are also involved in cell growth, cell death and production of heat. Mitochondria carries out cellular respiration for the production of ATP.

The chemiosmosis is the movement of ions down the electrochemical gradient across a semipermeable membrane bound structure. A classic example of this process is the production of ATP which occurs in the mitochondria of the cell. This process occurs due to $H^{+}$ ion gradient that is developed across the mitochondrial membrane. The protons diffuse from high proton concentration area to low proton concentration area, so that the electrochemical gradient gets established for ATP production.

The ATP synthase is the enzyme which is present in the mitochondrial inner membrane and uses protons to make ATP by chemiosmosis. It allows the movement of protons across membranes and simultaneously uses its energy to make ATP from ADP. Chemiosmosis generally occurs in mitochondria, chloroplasts and in bacteria.

Hence, the correct answer is option (C).

Note: Energy is produced in mitochondria due to the electrochemical proton gradient which is established across the mitochondrial membrane. The protons are pumped out by the enzyme ATP synthase. Before being pumped by ATP synthase, these protons along with some electrons pass through an ‘electron transport chain’ which is a series of oxidation-reduction reactions and aids in ATP production. The electron transport chain brings the protons and electrons down the gradient which are then passed to through the ATP synthase to form ATP.