the plant cell :: essays research papers

The Plant Cell Cell Wall Size: Around 1Â µ Basic Function: * Hold the shape of the cell. * Strengthen the cell. Covering the cell membrane of the plant cell, there is the cell wall. The cell wall is composed of two layers of rigid, hard cellulose embedded in compounds like 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 the growth of the cell. After the cell has stopped growing, a secondary cell wall forms. This secondary wall is made of lignin and cellulose, woven together tightly, to prevent further growth and to form and strong protective barrier. Cytoplasm Size: Unmeasurable Basic Function: * Helps dissolve waste products * Creates a "medium" for vesicles to travel through * Aids in cell metabolism * Serves as a home for the cytoskeleton. The cytoplasm is the jelly-like material that makes up much of the cell. It is 80% water and usually clear in color. It also contains many salts. The liquid portion is referred to as cytosol. In fact, "cytoplasm" means "cell substance." The cytoplasm is also the home of the cytoskeleton, a network of cytoplasmic filaments that are responsible for the movement of the cell. The cytoplasm is constantly moving and churning due to cytoplasmic streaming. Golgi Apparatus Size: Between 2 and 3Â µ Basic Function: * Serves as "processing center" for 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 packages proteins for secretion or storage in vesicles. Inside the membranes are sacs of fluid or gel-like substances. The Golgi Apparatus takes proteins in transport sacs from the endoplasmic reticulum and sends it through a series of these membranes. The proteins are then "modified"' as they pass from membrane to membrane. After the vesicle of proteins has finished its trip through the Golgi Apparatus, it buds off the organelle in 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 enters and exits the cell. * Separates cell from outer environment. On the outside of all cells, there is a layer of protein and lipid (fat) called the cell membrane or the plasma membrane. This membrane is found in ALL cells. The membrane is selectively permeable, meaning it allows some molecules to enter and some not to. The membrane allows molecules in through two forms