Before storage molecules can be used for energy, they first need to be broken down through a process called oxidation. Storage molecules like carbohydrates, fats, and proteins are initially large molecules that must be digested into smaller units (e.g., sugars, fatty acids, amino acids). These smaller molecules then undergo stepwise oxidation in cells, which involves transferring electrons and gradually releasing energy. This energy is captured in the form of high-energy molecules like ATP (adenosine triphosphate) through cellular processes including glycolysis, the citric acid cycle, and oxidative phosphorylation in mitochondria. Thus, the storage molecules must be enzymatically broken down and chemically converted to release usable energy for cellular activities.
Summary of Key Steps:
- Digestion: Large storage molecules are enzymatically broken into smaller subunits.
- Oxidation: These subunits are oxidized, transferring electrons and releasing energy.
- ATP Production: Energy from oxidation is converted into ATP, a usable form of cellular energy.
- Oxygen Role: In aerobic cells, oxygen accepts electrons at the end of the electron transport chain, facilitating complete oxidation of the molecules.
In essence, storage molecules need to be chemically transformed via enzymatic digestion and oxidation pathways before their stored chemical energy can be harnessed as ATP for cellular use.