Chemical reactions in a cell mainly take place in the cytoplasm, which is a jelly-like material inside the cell that contains dissolved nutrients, salts, and organelles. Many chemical reactions happen there, mediated by enzymes that catalyze specific reactions. In addition, specialized membrane-bound organelles have distinct sets of chemical reactions: for example, mitochondria contain enzymes for energy production, lysosomes have enzymes for digestion, and the endoplasmic reticulum and Golgi apparatus coordinate protein synthesis and sorting. The chemical organization of these compartments allows the cell to efficiently carry out a wide variety of reactions essential for survival, growth, and reproduction.