ATP AND OTHER ENERGY STORAGE MOLECULES

Objective of the discussion;

By the end of this discussion, the learner will be able to;

1. Explain the meaning of Redox potentials
2. Describe the term Biological oxidation
3. Differentiate between Enzymes and coenzymes
4. Identify the High energy compounds
5. Organization of electron transport chain

OXIDATION OF FOODSTUFFS-FIRST STAGE: Digestion in the gastrointestinal tract converts the macromolecules into small units. For example, proteins are digested to amino acids.  This is called primary metabolism.

SECOND STAGE: The products of digestion are absorbed, catabolized to smaller components, and ultimately oxidized to CO₂.  The reducing equivalents are mainly generated in the mitochondria by the final common oxidative pathway, citric acid cycle.  In this process, NADH and FADH₂ are generated.  This is called secondary or intermediary metabolism.

THIRD STAGE:  These reduced equivalents (NADH and FADH2) enter into the electron transport chain (ETC), or Respiratory chain, where energy is released.  This is the tertiary metabolism or internal respiration or cellular respiration.  The energy production by complete oxidation of one molecule of glucose is 2850 kJ/mol and that of palmitate is 9781 kJ/mol.  This energy is then used by body for synthetic reactions.

FOOD IS CATABOLIZED; energy from food is trapped as ATP; it is then used for anabolic reactions.  Phototrophs harvest the energy of light (plants). Chemotrophs harvest energy from oxidation of fuel molecules.