Redox terminology — In biochemical reactions, oxidation of a molecule is best defined as which change?

Introduction / Context:
Redox definitions underpin metabolism, from dehydrogenase reactions to the electron transport chain. Precise terminology helps avoid confusion when tracking electron flow and energy changes in pathways such as glycolysis, beta-oxidation, and the TCA cycle.

Given Data / Assumptions:

• Oxidation and reduction always occur together (as a redox pair).
• Electrons carry reducing power and potential energy.
• Proton transfer may accompany electron transfer but is not the defining feature of oxidation.

Concept / Approach:
Oxidation is loss of electrons (OIL), and reduction is gain of electrons (RIG). While some redox reactions are coupled to proton transfers (acid–base chemistry), the fundamental definition concerns electron movement, not proton count per se.

Step-by-Step Solution:

Verification / Alternative check:
Balance redox equations by electron bookkeeping; the side losing electrons corresponds to oxidation half-reaction, matching the definition.

Why Other Options Are Wrong:

Common Pitfalls:
Equating oxidation strictly with oxygen addition; while often correlated, oxidation can occur without oxygen involvement.

Final Answer:
Loss of electrons by the molecule.