Each of these reactions is involved in one of the four stages of metabolism shown in Figure 21.4. Identify the stage in which each reaction occurs.
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b. Oxidation of NADH coupled with synthesis of ATP

Verified step by step guidance

1. Understand the four stages of metabolism: (1) Digestion, (2) Acetyl-CoA production, (3) Citric acid cycle, and (4) Electron transport chain and oxidative phosphorylation. Each stage has specific chemical processes associated with it.
2. Recognize that the oxidation of NADH is a key process in the electron transport chain, which is part of the fourth stage of metabolism: oxidative phosphorylation.
3. Recall that during the electron transport chain, NADH is oxidized to NAD⁺, and the electrons released are transferred through a series of protein complexes in the mitochondrial membrane.
4. Understand that the energy released during the transfer of electrons is used to pump protons (H⁺) across the mitochondrial membrane, creating a proton gradient. This gradient drives the synthesis of ATP by ATP synthase.
5. Conclude that the oxidation of NADH coupled with the synthesis of ATP occurs during the fourth stage of metabolism: the electron transport chain and oxidative phosphorylation.

Key Concepts

Metabolism

Metabolism refers to the set of life-sustaining chemical reactions in organisms. It is divided into two main categories: catabolism, which breaks down molecules to produce energy, and anabolism, which uses energy to construct components of cells. Understanding metabolism is crucial for identifying how different biochemical reactions contribute to energy production and utilization in living organisms.

NADH and ATP

NADH (Nicotinamide adenine dinucleotide) is a key electron carrier in cellular respiration, playing a vital role in the transfer of electrons during metabolic reactions. ATP (Adenosine triphosphate) is the primary energy currency of the cell, providing energy for various cellular processes. The oxidation of NADH is coupled with ATP synthesis, highlighting the interconnectedness of electron transport and energy production.

Oxidative Phosphorylation

Oxidative phosphorylation is the final stage of cellular respiration, occurring in the mitochondria. It involves the transfer of electrons through the electron transport chain, leading to the pumping of protons across the mitochondrial membrane and creating a proton gradient. This gradient drives ATP synthesis via ATP synthase, making it essential for understanding how energy is produced in cells.