Cytoplasm is a homogeneous, generally clear jelly-like material that fills cells. The cytoplasm consists of cytosol and the cellular organelles, except the nucleus. The cytosol is made up of water, salts, organic molecules and many enzymes that catalyze reactions. The cytoplasm plays an important role in a cell, serving as a "molecular soup" in which the organelles are suspended and held together by a fatty membrane. It is found within the plasma membrane of a cell and surrounds the nuclear envelope and the cytoplasmic organelles.