Question

As per chemisomotic coupling hypothesis, in mitochondria, protons accumulate in the

• A. Outer membrane
• B. Inner membrane
• C. Intermembrane space
• D. Matrix

Answer 1

Answer: (C)

Intermembrane space

Chemiosmotic coupling hypothesis, proposed by Peter Mitchell (1961, 66) (Nobel Prize in 1978), is the most widely accepted theory for oxidative phosphorylation. Reduced NAD (i.e., NADH), released from Krebs' cycle, when enters in the ETS, transports three pairs of $H^{+}$ across the inner mitochondrial membrane to the intermembrane space. Similarly, NADH from glycolysis and ${FADH}_2$ from Krebs' cycle also transport pairs of $H^{+}$ into intermembrane space. Each molecule of NADH release from glycolysis or ${FADH}_2$ from Krebs' cycle transports two pairs of protons intermembrane space. This unidirectional flow of protons results in the accumulation of protons in the intermembrane space.

So, the correct answer is 'Intermembrane space'.