CoachAn organelle is a structure inside a cell with a definite composition and function; the membrane-bounded organelles are compartments whose interior differs in composition from the cytosol, the aqueous solution of the cytoplasm outside them. Membrane-bounded compartments: the nucleus, the endoplasmic reticulum, the Golgi apparatus, lysosomes, peroxisomes, mitochondria, and in plants the plastids and the vacuole. Organelles without a membrane: ribosomes, the centrosome, the cytoskeleton.
