Question

The process of synthesizing ATP from ADP and Pi coupled with electron transport chain is:

• A. Gluconeogenesis
• B. $\beta$-Oxidation
• C. Oxidative phosphorylation
• D. Reductive phosphorylation

Hint:

Oxidative phosphorylation = Electron Transport Chain (oxidation) + ATP Synthase activity (phosphorylation).
Consumes $\text{O}_2$ and produces majority of cellular ATP in aerobic organisms.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the me of the metabolic pathway in which ATP formation from ADP and inorganic phosphate ($\text{P}_i$) is driven by electron transfer along the mitochondrial respiratory chain.

Step 2: Key Formula or Approach:
Cellular respiration couples exergonic oxidation of electron donors ($\text{DH}, \text{FADH}_2$) through the Electron Transport Chain (ETC) to the phosphorylation of ADP via ATP synthase, driven by a proton electrochemical gradient ($\Delta p$).

Step 3: Detailed Explation:

• Coupled Mechanism: High-energy electrons derived from metabolic substrates are transferred through respiratory complexes I, II, III, and IV embedded in the inner mitochondrial membrane to termil electron acceptor oxygen ($O_2$).

• Proton Gradient Generation: As electrons travel down favorable redox gradients, complexes I, III, and IV pump protons ($H^+$) from the matrix into the intermembrane space, generating a proton-motive force.

• ATP Synthesis: Protons flow back into the matrix down their electrochemical gradient through Complex V ($\text{F}_0\text{F}_1$-ATP Synthase). This mechanical rotation drives the phosphorylation reaction: \[ \text{ADP} + \text{P}_i + H^+_{\text{out}} \xrightarrow{\text{ATP Synthase}} \text{ATP} + \text{H}_2\text{O} + H^+_{\text{in}} \]
• Definition: This combined electron transfer and coupled ATP synthesis is universally known as oxidative phosphorylation.

Step 4: Fil Answer:
The coupling of ATP synthesis to electron transport across the membrane is termed oxidative phosphorylation.