Question

(g)

Within the electron transport chain, complex ____ represents the entry port for electrons from NADH while complex ____ represents the entry point for electrons from FADH₂.

Group of answer choices

I; III

II; III

I; II

II; IV

III; IV

(h)

You have a solution that contains the pyruvate dehydrogenase complex and all of the enzymes of the citric acid cycle, but none of the intermediates of the citric acid. If you add 3.0 mM each of pyruvate, coenzyme A, NAD⁺, FAD, GDP, and P_i (inorganic phosphate), how much CO₂ would be produced?

Assume all of the enzymes are 100% active.

Group of answer choices

0 mM CO₂

1.5 mM CO₂

3.0 mM CO₂

6.0 mM CO₂

9.0 mM CO₂

_(I)

You have a solution that contains the pyruvate dehydrogenase complex and all of the enzymes of the citric acid cycle, but none of the intermediates of the citric acid. If you add 3.0 mM each of succinate, pyruvate, coenzyme A, NAD⁺, FAD, GDP, and P_i (inorganic phosphate), how much CO₂ would be produced?

Assume all of the enzymes are 100% active.

Hint: Read questions 21 and 22 carefully, the experimental conditions are different - see succinate in question 21!

Group of answer choices

0 mM CO₂

1.5 mM CO₂

3.0 mM CO₂

6.0 mM CO₂

9.0 mM CO₂

Answer 1

Within the electron transport chain, complex I represents the entry port for electrons from NADH while complex II represents the entry point for electrons from FADH2.

h)

Correct answer is 3.0 mM of CO2

Explanation:

Conversion of pyruvate to Acetyl Co-A releases 1 mole of CO2 for per mole of pyruvate. Since 3.0mM of pyruvate is provided, 3.0 mM of CO2 is produced. Since no intermediates are present and the first reaction of TCA cycle requires oxaloacetate intermediate, no reaction will take place. Thus no CO2 is produced in TCA cycle

(I)

Correct answer is 9.0 mM of CO2

Explanation :

Conversion of pyruvate to Acetyl Co-A releases 1 mole of CO2 for per mole of pyruvate. Since 3.0mM of pyruvate is provided, 3.0 mM of CO2 is produced. Since 3.0 mM succinate is provided, it will form 3.0 mM of oxaloacetate ultimately. 1mole of Acetyl Co-A fuses with 1 mole of Oxaloacetate to produce 2 moles of CO2. Thus 3.0 mM of Acetyl Co-A will combine with 3.0mM of Oxaloacetate to give 6.0mM of CO2 . In total, 3 + 6 = 9.0 mM of CO2 will be produced.

PS - In this question, to be exact 15 mM of CO2 should be produced since 3.0mM of pyruvate gives rise to 3.0 mM of CO2  and 3.0mM of Acetyl-CoA which is also shuttled to TCA. Thus the total concentration of Acetyl Co-A becomes 6.0mM which will give rise to 12 CO2 . In total , it becomes 15.0 mM of CO2 .