Final answer:
The substrate is oxidized and the coenzyme, NAD+, is reduced to NADH during the enzymatic reaction, converting the coenzyme from state 1 to state 2. The correct answer is option 2.
Step-by-step explanation:
The reaction involves a coenzyme that aids in the catalysis of a catabolic process. In the diagram, the coenzyme starts in state 2 (denoted by the oxidized form) and, after the reaction, transitions to state 1 (the reduced form). This change in state signifies that the coenzyme has accepted a pair of electrons from the substrate, indicating a reduction.
Conversely, the substrate in the reaction loses electrons, implying oxidation. Oxidation refers to the loss of electrons or an increase in oxidation state. Therefore, the substrate is oxidized as part of this catabolic process.
Enzymes often rely on coenzymes like NAD+ (Nicotinamide adenine dinucleotide) or FAD (Flavin adenine dinucleotide) to facilitate oxidation-reduction reactions. These coenzymes undergo a reversible change in redox state during the catalytic process, shuttling electrons between substrates, and are essential for many metabolic pathways in cells.
Hence, in this specific enzymatic reaction, the correct description is that the substrate is oxidized, while the coenzyme is converted from state 2 (oxidized) to state 1 (reduced).