The cell (from Latin cella, meaning "small room") is the basic structural, functional, and biological unit of all known organisms. All cells have the same basic structure. They are all surrounded by a cell membrane and contain cytoplasm and organelles. The cell membrane is made up of phospholipids - proteins and controls substances, which move in and out of the cell. The structure of the cell membrane is referred to as the Fluid Mosaic Model. Cells provide six main functions. They provide structure and support, facilitate growth through mitosis, allow passive and active transport, produce energy, create metabolic reactions and aid in reproduction.