Cell Membrane: separates the inside of the cell from the outside environment and controls the flow of materials into and out of the cell. Cytoplasm: includes the cytosol (liquid part), organelles and other life-supporting materials. Vesicles: membrane-covered sacs that transport and/or store materials inside the cell. Also help materials cross the cell membrane to enter or leave cell. Vacuoles: contain water and other materials. Used to store or transport smaller molecules. Plant cells have 1 large vacuole animal cells have many small vacuoles. Cytoskeleton: Helps cell maintain its structure and provide tracks for vesicles and organelles to move.