Metabolism involves anabolic and catabolic processes. Anabolism involves building complex compounds from simpler ones and requires energy, such as photosynthesis. Catabolism involves breaking down complex compounds into simpler ones and releases energy, such as glycolysis. Enzymes act as biocatalysts to regulate chemical reactions in metabolism. Factors like temperature, pH, enzyme and substrate concentrations affect enzymatic reactions. Aerobic respiration provides more energy through glycolysis, the Krebs cycle, and electron transport, while anaerobic respiration through fermentation provides less energy without oxygen. Amino acids are synthesized through transcription and translation and broken down through deamination and the urea cycle. Fatty acid synthesis begins with acetyl-Co