CHAPTER 13: CELLULAR METABOLISM
Metabolic reactions contribute to homeostasis by harvesting chemical energy from consumed nutrients to contribute to the body’s growth, repair, and normal functioning.
Food molecules absorbed have 3 main fates:
1. Most food molecules are used to SUPPLY ENERGY to sustain life processes.
2. Some food molecules serve as BUILDING BLOCKS for synthesis of more complex structural and functional molecules.
3. Other food molecules are STORED FOR FUTURE USE .
Metabolic Reactions : refers to all the chemical reactions that occur in the body.
There are 2 types: Catabolism and Anabolism
1) Catabolism: chemical reactions that break down complex organic molecules into simpler ones. These reactions overall are Exergonic meaning they produce more energy than they consume releasing the chemical energy stored in organic molecules. Catabolism is referred to as Decomposition.
Examples:
2) Anabolism : chemical reactions that combine simple molecules and monomers to form the body’s complex structural and functional components. These reactions are Endergonic as they consume more energy then they produce. Anabolism is referred to as Synthesis.
Examples:
Metabolism is a balance act between catabolism and anabolism. Catabolic reactions can be occurring in the mitochondria of a cell at the same time as anabolic reactions are taking place in the endoplasmic reticulum. This is known as dynamic equilibrium.
Coupling of Catabolism and Anabolism by ATP
Chemical reactions depend on the transfer of energy from one molecule to another. ATP most often performs this task and is referred to as the “ energy currency ” of a living cell. Recall: a molecule of ATP consists of an Adenine molecule, a ribose molecule, and 3 phosphate groups bonded to one another.
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