Question

Which coenzyme is a reactant in the oxidation of a nutrient, \(\mathrm{NAD}^{+}\) or NADH? What is the reason for your answer?

Short answer

\(\text{NAD}^{+}\) is the reactant because it accepts electrons during the oxidation of nutrients.

Step-by-step solution

Understand the Redox Process

Oxidation-reduction (redox) reactions involve the transfer of electrons. In the context of nutrient oxidation, a coenzyme is required to accept electrons. The electron acceptor is the oxidizing agent.

Identify the Coenzymes

Two related coenzymes involved in cellular metabolism are \(\text{NAD}^{+}\) (nicotinamide adenine dinucleotide) and NADH (the reduced form of \(\text{NAD}^+\)).

Determine the Electron Acceptor

\(\text{NAD}^{+}\) acts as an electron acceptor and is involved in the oxidation of nutrients. In this process, \(\text{NAD}^{+}\) gains electrons and is reduced to NADH.

Summarize the Role of \(\text{NAD}^+\)

\(\text{NAD}^+\) is required as a reactant in the oxidation of nutrients because it accepts electrons, thereby facilitating the oxidation process.

State the Conclusion

The coenzyme \(\text{NAD}^{+}\) is a reactant in the oxidation of nutrients because it functions as the electron acceptor and is reduced to NADH in the process.

Key concepts

Oxidation-Reduction Reactions

Oxidation-reduction reactions, also called redox reactions, play a crucial role in many biological processes. In simple terms, these reactions involve the transfer of electrons from one molecule to another. The molecule that loses electrons is said to be oxidized, while the molecule that gains electrons is reduced. It’s helpful to remember this through the acronym OIL RIG - Oxidation Is Loss, Reduction Is Gain.

For instance, during cellular respiration, glucose is oxidized to carbon dioxide. This means glucose loses electrons. Conversely, oxygen is reduced to water by gaining those electrons.

Understanding redox reactions is essential when studying cellular metabolism because these reactions are at the heart of energy production within cells. Without these reactions, cells wouldn't efficiently harness energy from nutrients.

Electron Acceptor

In the context of redox reactions, an electron acceptor is a molecule that gains electrons during the reaction. This is a critical component because the entire process hinges on the transfer of electrons.

One of the most important electron acceptors in cellular metabolism is \(\text{NAD}^+\) (nicotinamide adenine dinucleotide). This coenzyme plays a significant role in transferring electrons during the breakdown of nutrients.

When \(\text{NAD}^+\) accepts electrons, it is reduced to NADH. By doing so, it facilitates the overall oxidation process where a nutrient is oxidized. Essentially, \(\text{NAD}^+\) becomes NADH by gaining electrons, temporarily storing energy that will later be used by the cell for different processes, such as ATP production.

Think of \(\text{NAD}^+\) as a shuttle that carries electrons from one reaction to another, a crucial step for maintaining the balance and flow of cellular metabolism.

Cellular Metabolism

Cellular metabolism involves a series of chemical reactions that occur within cells to maintain life. These reactions are divided into two main categories: catabolic reactions, which break down molecules to produce energy, and anabolic reactions, which use energy to build complex molecules.

During catabolism, nutrients such as glucose are broken down, releasing energy. In this process, \(\text{NAD}^+\) accepts the electrons removed from nutrients, becoming NADH. This is crucial for the oxidation of nutrients because it enables the flow of electrons, which is needed for energy production.

One notable example is the process of glycolysis, where glucose is converted into pyruvate. Here, \(\text{NAD}^+\) is reduced to NADH, capturing the energy released during glucose breakdown. Later, NADH will donate these electrons in the electron transport chain, driving the production of ATP, the main energy currency of the cell.

In summary, without the vital role of \(\text{NAD}^+\) in accepting electrons, the energy from nutrient breakdown would not be harnessed efficiently. This makes \(\text{NAD}^+\) indispensable for proper cellular metabolism and energy production.