CH 09: Cellular Respiration: Harvesting Chemical Energy

Catabolism and Energy

Metabolic reactions either involve the buildup or breakdown of molecules.

Catabolism - Breaking of larger molecules into smaller ones.

Anabolism - Building of larger molecules from smaller ones.

Anabolic reactions are endergonic and require ATP.

Catabolic reactions allow chemical energy to be released by breaking bonds to be transferred to ATP.

Different catabolic pathways are possible in living cells, depending on whether O2 is present and whether the cells have mitochondria. Prokaryotic cells will still do cellular respiration, but it will not involve oxygen or the use of mitochondria which Prokaryotes do not contain.

These pathways involve the breaking of organic molecules to extract energy to do work. In addition, some energy is lost as heat, and waste products, molecules with less energy, are also generated.

Fermentation - Catabolic pathway in which the organic molecule is a sugar. The...