Question

How many $ATPs$ are formed per glucose molecule in Krebs’ cycle?

• A. $2$
• B. $24$
• C. $6$
• D. $28$

Answer 1

Answer: (B)

$ATP$ Production in respiration
I. Giycoiysis :
1. $PGAL$ to $BPGA:2NADH\to 6ATP$
2. $BPGA$ to $3PGA\to 2ATP$
3. $PEP$ to $PA\to 2ATP$
$2ATP$ are utilised, so net gain $\to 8ATP$ $II$. PA to Acetyl CoA: $2NADH\to 6ATP$
$III$. Krebs' cycle:
1. Isocitrate to $\alpha$-ketoglutarate: $2NADH\to 6ATP$
2. $\alpha$-Ketoglutarate to succinyl $CoA:2NADH\to 6ATP$
3. Succinyl CoA to succinic acid $\to 2ATP$
4. Succinic acid to fumaric acid : $2FAD{H}_2\to 4ATP$ 5. Malic acid to $OAA:2NADH\to 6ATP$
Net gain in Krebs’ cycle $\to 24ATP$
Oxidation of one molecule of pyruvic acid produces $15ATP$
Oxidation of one molecule of acetyl CoA produces $12ATP$