Question

During complete metabolism of glucose, the number of ATP formed is

• A. 2
• B. 12
• C. 36
• D. 44

Answer 1

Answer: (C)

36

There is a gain of $2$ ATP molecules during glycolysis and $2$ ATP(GTP) molecules during double Krebs cycle. A total of $10$ ${NADH}_2$ molecules are formed in aerobic respiration. Thus, the net gain from complete oxidation of a molecule of glucose in muscle and nerve cells is 36 ATP molecules ($10$ ${NADH}_2=30ATP,2{FADH}_2=4ATP$, four formed by substrate-level phosphorylation in glycolysis and Krebs' cycle and two consumed in transport of the ${NADH}_2$ molecules into mitochondria). In aerobic prokaryotes, heart, liver and kidneys, $38$ ATP molecules are produced per glucose molecule oxidised. passage of ATP molecules from inside of mitochondria to the cytoplasm is through facilitated diffusion.

Thus, there is a net gain of $36$ or $38$ ATP molecules depending upon the type of aerobic respiration.

[Note: $1{NADH}_2=3ATP$ and $1{FADH}_2=2ATP$].

So the correct answer is '36'.