SME
Biochemistry · Problem type
ATP from NADH and FADH₂
Use this for “Oxidizing one pyruvate completely makes 4 NADH, 1 FADH₂ and 1 GTP. How many ATP is that?”
Chart
Total ATP: ATP = 32
This is an example. Type your own values to start a new problem.
ATP
=
rN
×
NADH
+
rF
×
FADH₂
+
ATPd
ATPN
ATP from NADH
calculated
ATPF
ATP from FADH₂
calculated
Formulas
ATPN = rN × NADH
25 = 2.5 × 10
ATPF = rF × FADH₂
3 = 1.5 × 2
ATP = ATPN + ATPF + ATPd
32 = 25 + 3 + 4
Assumptions
•
Oxidative phosphorylation gives about 2.5 ATP per NADH and 1.5 per FADH₂ (older books use 3 and 2, giving 36–38 per glucose).
•
GTP from the citric acid cycle counts as one ATP; ATP spent along the way is taken off the direct count.
•
With the glycerol-phosphate shuttle, glycolysis’s NADH enters as FADH₂: count those 2 as FADH₂.
Step-by-step
WE KNOW
NADH = 10, FADH₂ = 2, ATPd = 4, rN = 2.5, rF = 1.5
FIND
ATP from NADH (ATPN), ATP from FADH₂ (ATPF), total ATP (ATP)
Step 1 · Find ATP from NADH (ATPN)
Use ATPN = rN × NADH
Each NADH passes two electrons into Complex I; they pump enough H⁺ for about 2.5 ATP.
ATPN = 2.5 × 10
ATPN = 25
Step 2 · Find ATP from FADH₂ (ATPF)
Use ATPF = rF × FADH₂
FADH₂ enters at Complex II, which pumps no H⁺, so each gives less: about 1.5 ATP.
ATPF = 1.5 × 2
ATPF = 3
Step 3 · Find total ATP (ATP)
Use ATP = ATPN + ATPF + ATPd
Add the ATP from both carriers to the ATP and GTP made directly.
ATP = 25 + 3 + 4
ATP = 32
Check
Put the numbers back in. Both sides should match.
25 = 2.5 × 10 ✓
3 = 1.5 × 2 ✓
32 = 25 + 3 + 4 ✓
Topic check
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