Chapter 7.6: Energy Yield of Aerobic Respiration

Question 1

Why is the theoretical yield of ATP in respiration for eukaryotes less than that of bacteria?

Answer 1

o 32 ATP for respiration is accurate for bacteria, but not for eukaryotes because the NADH produced in the cytoplasm by glycolysis needs to be transported into the mitochondria by active transport, which costs one ATP per NADH transported  Reduces predicted yield for eukaryotes to 30 ATP

Question 2

What is the theoretical yield of ATP in respiration for prokaryotes and eukaryotes?

Answer 2

32 for prokaryotes and 30 for eukaryotes

Question 3

What is the actual measurement of the P/O ratio?

Answer 3

 Actual measurements of the P/O ratio have been problematic, but now appear to be at most 2.5

Question 4

What is the P/O ratio?

Answer 4

• The value for the amount of ATP synthesized per O₂ molecule reduced is called the phosphate-to-oxygen ratio (P/O ratio)

Question 5

What is the problem with the theoretical calculation of ATP yield for respiration?

Answer 5

• When theoretical calculations were first made, we lacked detailed knowledge of the respiratory chain, and the mechanism for coupling electron transport to ATP synthesis
  
  • Since redox reactions occur at the three sites for NADH and two sites for FADH₂, it was assumed that three molecules of ATP were produced per NADH and two per FADH₂
    
    • This was overly simplistic