How Many ATP? ✏ Biology In a Nutshell

Rucete ✏ Biology In a Nutshell

1. ATP Yield from Cellular Respiration

 

ATP is generated at different stages of cellular respiration from the breakdown of glucose.

 

Breakdown of ATP Production per Stage:

Stage	FADH₂ Produced	NADH Produced	ATP Yield
Glycolysis	-	2 NADH	6 ATP (minus 2 ATP used)
Glycolysis (Direct ATP Production)	-	-	2 ATP
Pyruvate → Acetyl-CoA	-	2 NADH	6 ATP
Krebs Cycle (Direct ATP Production)	-	-	2 ATP
Krebs Cycle (NADH Contribution)	-	6 NADH	18 ATP
Krebs Cycle (FADH₂ Contribution)	2 FADH₂	-	4 ATP
Total Theoretical ATP Yield	-	-	36 ATP

 

2. ATP Loss in Glycolysis

• During glycolysis, 2 ATP are consumed when NADH is transported to the mitochondria for oxidative phosphorylation.
• This reduces the net ATP yield from 38 ATP to 36 ATP.

 

 

3. Actual ATP Yield

• The theoretical ATP yield is 36 ATP per glucose molecule.
• However, due to mitochondrial efficiency and biochemical competition, the real ATP yield is closer to ~30 ATP.

 

 

4. Summary of Cellular Respiration

1. Glycolysis (Cytoplasm):
   • Produces 2 ATP and 2 NADH (6 ATP, but 2 ATP are lost in transport).
2. Pyruvate to Acetyl-CoA (Mitochondria):
   • Produces 2 NADH (6 ATP).
3. Krebs Cycle (Mitochondria):
   • Produces 2 ATP, 6 NADH (18 ATP), and 2 FADH₂ (4 ATP).
4. Oxidative Phosphorylation (Mitochondrial Membrane):
   • Uses NADH and FADH₂ to generate ATP through the electron transport chain.
     

 

 

In a nutshell

• Glycolysis = 2 ATP
• Krebs Cycle = 2 ATP
• NADH & FADH₂ → 32 ATP in Oxidative Phosphorylation