The electromotive force generated by the electron transfer chain, known as the proton motive force (PMF), drives key cellular processes in mitochondria. This force arises from electron flow through the electron transport chain (ETC), pumping protons across the inner mitochondrial membrane to create electrochemical gradients.

Option Analysis

(A) It is used for the synthesis of ATP.

Correct. The PMF powers ATP synthase via chemiosmosis, where protons flow back into the matrix, rotating the enzyme to convert ADP + Pi to ATP.

(B) It is not used for active transport process.

Incorrect. The PMF drives active transport of ions, metabolites, and proteins across the membrane, such as via proton-coupled antiporters and symporters.

(C) It includes a pH gradient component.

Correct. PMF comprises a ΔpH (pH gradient, matrix more alkaline) from proton accumulation in the intermembrane space.

(D) It does not include an electrical potential gradient component.

Incorrect. PMF includes Δψ (membrane potential, matrix negative) due to charge separation from proton pumping.

The electromotive force electron transfer chain generates—known as proton motive force (PMF)—powers ATP production in mitochondria during oxidative phosphorylation. This electrochemical gradient, formed by ETC complexes I, III, and IV pumping protons, is essential for cellular energy.

PMF Components

PMF (Δp = Δψ - 2.303 (RT/F) ΔpH) includes:

• ΔpH gradient: Protons create acidic intermembrane space (pH ~6.8) vs. alkaline matrix (pH ~7.8).
• Δψ electrical potential: Negative matrix (~-140 to -180 mV) from charge imbalance.

Both drive protons through ATP synthase.

Applications in Biology

• ATP synthesis: 3-4 H⁺ per ATP via F₀F₁-ATPase rotation.
• Active transport: Powers metabolite exchange (e.g., ADP/ATP, Pi/H⁺).

This mechanism is critical for CSIR NET questions on bioenergetics, linking ETC to chemiosmosis.