Question

Terminal oxidation comprises of
A) Synthesis of metabolic water
B) Electron transport
C) Oxidative phosphorylation
D) All of the above

Answer 1

Hint: In order to survive, a living cell has to undergo a sequence of several biochemical reactions such as Krebs Cycle, Glycolysis, etc.

Complete Answer:
Option A: When the glucose molecule undergoes respiratory breakdown in presence of the oxygen molecule, the process is known as oxidation.
- Every single oxidation process involves the release of 2 hydrogen atoms which is further responsible for the reduction of several co-enzymes such as FAD or $NAD^+$. Both the reduced substrates released during Krebs Cycle and Glycolysis finally facilitates the reduction of oxygen back to water.
- This transfer of electron and hydrogen from $H^+$, NADH, or FADH to Oxygen is a complex process as the direct transfer from co-enzyme to the oxygen becomes thermodynamically impossible to attain.

Option B: In order to facilitate the above transfer, many intermediate cytochromes and other respective carriers arrange themselves in a series which facilitates electron transfer between NADH and $O_2$ or $FADH_2$ and $O_2$.
- This sequence of the electron carriers is collectively represented as the Electron Transport System. This process proceeds from carriers representing low redox potential to those featuring high redox potential.

Option C: The transport of the electrons down the energy gradient through the ETC results in the conversion of the ADP and inorganic phosphates back to ATP. This conversion process is referred to as oxidative phosphorylation.

Option D: As all the above statements are correct, therefore, this is the correct option.

Thus, the correct option is D) All of the above.

Note: This process of terminal oxidation occurs towards the end of the process of cellular respiration. In the course of this reaction, several intermediates such as succinic acid, pyruvic acid, oxalic acid, and isocitric acid undergo oxidation.