The cytoplasm of the cells consists of two main elements: cytosol and the organelles. The cytosol is the part of the cytoplasm that surrounds organelles. It is a mixture of cell substances dissolved in water. In prokaryotes, it has an important role in metabolism since most of the reactions take place in the cytosol. Unlike prokaryotes, eukaryotes have organelles, so not all of the reactions take place in the cytosol. Some of them occur in the organelles.