Question

The oxidation of one NADH \(_{2}\) yields (a) 18 ATP (b) \(6 \mathrm{ATP}\) (c) 3 ATP (d) \(2 \mathrm{ATP}\)

Short answer

The oxidation of one NADH2 yields 3 ATP, hence the correct option is (c) 3 ATP.

Step-by-step solution

Recall Facts about Bioenergetics

To solve this exercise, no calculations are needed. Instead, the student must remember basic facts about cellular respiration. Specifically, when one molecule of NADH2 is oxidized in the electron transport chain, how much ATP is produced? This is a very crucial information in understanding bioenergetics.

Choose the Correct Option

From the recalled fact, it's known in cellular respiration, the oxidation of one NADH2 molecule yields 3 ATP. Therefore, the correct choice is option (c).

Key concepts

Cellular Respiration

Cellular respiration is a vital biological process in which cells convert nutrients into energy. It allows cells to break down glucose and other food molecules in the presence of oxygen to release energy. This energy is then used to produce adenosine triphosphate (ATP), which serves as a universal energy currency for cellular activities.

The process can be split into three main stages: glycolysis, the Krebs cycle (also known as the citric acid cycle), and the electron transport chain. Glycolysis takes place in the cytoplasm, where glucose is broken down into pyruvate, yielding some ATP and electron carriers, such as NADH. The pyruvate is then transferred to the mitochondria, where the Krebs cycle produces more NADH and another carrier called FADH2.

Understanding cellular respiration is crucial not only for bioenergetics but also for fields like exercise physiology, nutrition, and medicine. A firm grasp of this process explains how our bodies convert the food we eat into the energy needed for everything from cellular repair to running a marathon.

Electron Transport Chain

The electron transport chain (ETC) is the final and most complex stage of cellular respiration. Housed in the inner mitochondrial membrane, it comprises a series of protein complexes and electron carriers. These components work together to transfer electrons from NADH and FADH2 to oxygen, which is reduced to water.

As electrons move through the ETC, protons are pumped from the mitochondrial matrix to the intermembrane space, creating a gradient. This gradient generates a driving force called the proton motive force, essential for ATP synthesis.

Understanding the ETC is crucial because it underpins the concept of oxidative phosphorylation—the process by which the energy released from electrons is used to make ATP. The electron transport chain is an excellent example of how intricately molecular processes are tied to energy production in our cells.

ATP Production

ATP production is the goal of cellular respiration, and it is primarily achieved through a process known as oxidative phosphorylation, which occurs in the mitochondria. As established, the electron transport chain creates a proton gradient across the mitochondrial membrane. ATP synthase, a remarkable enzyme, harnesses this gradient to catalyze the synthesis of ATP from adenosine diphosphate (ADP) and an inorganic phosphate.

To put it in context, the oxidation of one NADH molecule in the electron transport chain contributes to the production of approximately 3 ATP molecules—the answer to our original exercise. This efficiency of energy conversion highlights ATP's importance as a readily accessible energy source for myriad cellular functions, from muscle contractions to active transport across cell membranes.

A comprehensive understanding of ATP production is essential not only for biology students but also for professionals in health and sports sciences, as it explains how energy is managed and utilized at the cellular level.