Memory Game Microbiology chapter 3Online version Cell structure by misael Lopez Helps maintain the shape of a cell externally and protects it from physical or chemical damage. A rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. Cytoskeleton •Structural support •Transport of molecules •Receptors for hormones •Surface antigens Cell wall - identifies bacteria as either gram stain positive or negative Gram positive Plasma Proteins Very dynamic and capable of reorganization. Helps cells maintain their shape Cell membrane A dense gelatinous matrix composed of 70% to 80% water. the site for most of the enzymatic reactions and metabolic activity of the cell. Cytoplasm Bacterial cell wall - a fluid mosaic made up of three types of organic molecules. - a semipermeable membrane surrounding the cytoplasm of a cell - thick peptidoglycan layer, external to plasma membrane. Gram negative - Thin peptidoglycan layer in the periplasmic space - large periplasmic space