The plant cellCell wallSize: about 1μBasic function:* Maintains the shape of the cell.* Strengthens the cell.Covering the cell membrane of the plant cell, is the cell wall. The cell wall is composed of two layers of hard, rigid cellulose embedded in compounds such as pectin and lignin. Pores in the cell wall allow molecules to pass through. The cell wall has two parts. The primary cell wall is formed during cell growth. After the cell stops growing, a secondary cell wall forms. This secondary wall is made up of lignin and cellulose, tightly woven together, to prevent further growth and form a strong protective barrier. Cytoplasm Size: Unmeasurable Basic Function:* Helps dissolve waste products* Creates a "medium" through which vesicles can travel* Aids in cellular metabolism* Serves as a site for the cytoskeleton. The cytoplasm is the gel-like material that makes up much of the cell. It is made up of 80% water and is usually transparent in color. It also contains many salts. The liquid part is called cytosol. In fact, "cytoplasm" means "cellular substance". The cytoplasm is also the home of the cytoskeleton, a network of cytoplasmic filaments responsible for the movement of the cell. The cytoplasm is in constant motion and agitation due to cytoplasmic flow.Golgi apparatusSize: Between 2 and 3μBasic function:* Serves as a "processing center" for the cell.* Packages and processes new proteins.* Prepares proteins for secretion or storage. The Golgi apparatus is a series of stacked membranes in the cytoplasm that package proteins for secretion or storage in vesicles. Inside the membranes there are pockets of fluid or gelatinous substances. The Golgi apparatus picks up proteins in transport sacs from the endoplasmic reticulum and sends them across a series of these membranes. The proteins are then "modified" as they pass from membrane to membrane. After the protein vesicle finishes its journey through the Golgi apparatus, it buds from the organelle into a Golgi sac, ready to be stored or transported to other parts of the body. Cell membrane Size: 7 to 8 NM (nanometers) Basic function: * Controls what goes in and out of the cell.* Separates the cell from the external environment. On the outside of all cells is a layer of proteins and lipids (fat) called the cell membrane or plasma membrane. This membrane is found in ALL cells. The membrane is selectively permeable, meaning it allows some molecules to enter and others not. The membrane allows molecules to enter through two forms