Cytoplasm

The cytoplasm is all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are the cytosol (a gel-like substance), the cell's internal sub-structures, and various cytoplasmic inclusions. The cytoplasm is about 80% water and is usually colorless. The cytosol or cytoplasmic matrix or groundplasm, remains after the exclusion of the cell organelles and cytoplasmic inclusions. Microscopically it is a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, plant plastids, lipid droplets, and vacuoles. Many cellular activities take place within the cytoplasm, such as many metabolic pathways, including glycolysis, photosynthesis, and processes such as cell division. The concentrated inner area is called the endoplasm and the outer layer is called the cell cortex, or ectoplasm. Movement of calcium ions in and out of the cytoplasm is a signaling activity for metabolic processes. In large animal and plant cells, amoebae and slime molds, movement of the cytoplasm around organelles and vacuoles is known as cytoplasmic streaming.