Question

The chemiosmotic theory is based on ____________.

• A. accumulation of $N{a}^{+}$ ions
• B. accumulation of $K^{+}$ ions
• C. proton gradient
• D. membrane potential

Answer 1

The correct option is C proton gradient

The chemiosmotic theory is based on the proton gradient. It explains the synthesis of ATP.

$NADH+H^{+}$ and $FAD{H}_2$ are produced during glycolysis and the Krebs cycle. They get oxidised and release electrons that pass through the various complexes of the electron transport chain present in the inner mitochondrial membrane. The energy available in the electrons is used to pump the protons from the matrix of mitochondria to the intermembrane space. These protons get accumulated in the intermembrane space. This increases the concentration of protons in the intermembrane space and creates a driving force. This concentration difference is called proton gradient. The protons move back into the matrix of mitochondria through complex V.

Complex V has two components, $F_0$ and $F_1$. $F_0$ forms the channel for the passage of protons and $F_1$ has a site for the synthesis of ATP from ADP and inorganic phosphate. These protons provide enough energy for the ADP to combine with inorganic phosphate to form ATP in the presence of ATP synthase enzyme.