Question

Choose the correct answers from the alternatives given :
Of the 36 ATP molecules that are produced during the complete breakdown of glucose, most are due to the action of

• A. substrate-level phosphorylation
• B. electron transport system
• C. chemiosmotic phosphorylation
• D. both (b) and (c)

Answer 1

The correct option is D both (b) and (c)

• Substrate level phosphorylation is the part of glycolysis reaction whihc will give the cell 2 molecules of ATP at the end of the reaction.
• Electron transport system is the transport system that is present in the mitochondrial membrane where it transports the electrons and hydronium ions from NADH and FAD through various complex of the chain.
• In chemiosmotic phosphorylation the $F_1$-$F_0$ complex is used for the synthesis of one molecule of ATP for every 2 hydronium ion that is transported through the complex from the intermembrane matrix.
  
• For each NADH transported through the chain 3 times 2 hydronium ions are released which means every molecule of NADH produces 3 molecules of ATP. For every FADH molecules passed 2 times 2 hydronium are released which means that every molecule of FADH gives 2 ATP molecules.
• Therefore when per pyruvic acid after going under kerb cycle gives 4 NADH and 1 FADH molecule that gives the cell with 12 ATP and 2 ATP molecules respectively per cycle.
• Therefore ETS and the chemisomotic phosphorylation give the major contribution in the formation of ATP i.e. 15 ATP per cycle.
• Therefore the answer option 'both (b) and (c)' is correct.