Question

1. Let’s use glucose as the metabolic fuel for aerobic respiration.

1. How many ATPs would be formed if NAD⁺were the sole electron carrier cofactor formed throughout the metabolic pathways of glycolysis, the citric acid cycle, and oxidative phosphorylation?

b.   How many H⁺would have to be pumped from the intermembrane space and into the matrix for the ATP synthase to generate all of these ATPs?

c. Answer question 2 (part a and b) but replace NAD⁺with FAD.

d. In ATP synthase, describe the process that promotes the conformational changes that facilitates the catalyzed reaction.

Answer 1

Q1. a). To complete oxidation of glucose ( glycolysis and TCA ) 10 NADH molecules are produced.

In recent studies 1 NADH molecule gives 2.5 ATP. so, 10 NADH will give 25 ATP.

Altogether, to complete oxidation of glucose 4 ATP + 25 ATP = 29 ATP will produced, if NAD+ is the sole electron carrier.

b). 4 H+ would have to be pumped from the intermembrane space and into the matrix for the ATP synthase to generate 1 ATP. So, to synthesised 25 ATP, 25*4 = 100 H+ would have to be pumped from the intermembrane space and into the matrix for the ATP synthase to generate all of these ATP.

Q2. If FAD is the only electron carrier.

a). To complete oxidation of glucose ( glycolysis and TCA ) 2 FADH2 molecules are produced.

1 FADH2 will form 1.5 ATP. So, 2 FADH2 will give 3 ATP.

Altogether, to complete oxidation of glucose 4 ATP + 3 ATP = 7 ATP will produced, if FAD+ is the sole electron carrier.

b). 4 H+ would have to be pumped from the intermembrane space and into the matrix for the ATP synthase to generate 1 ATP. So, to synthesised 3 ATP, 3*4 = 12 H+ would have to be pumped from the intermembrane space and into the matrix for the ATP synthase to generate all of these ATP.

Q3. ATP synthase have 2 parts Fo and F1 particles.

Fo is embedded in the inner membrane and F1 protudes to the matrix of mitochondria.

Fo is made of 12 identical subunit called , c. The Fo is linked by a gama-subunit to the F1 parts, F1 is composed of 3 pairs of alpha and beta subunits. Others subunit 'a' and 'b' connects F1 knob to the membrane. WhwnProtons moves from intermembrane to the matrix along the concentration gradient through the 'a' subunit to the 'c' subunits making the 'c' subunits to rotates. This rotation makes the axis to rotate i.e., gama subunit, but the F1 does not rotate. when the axis rotates change the conformation of F1 particle allowing to catalyse the formation of ATP.