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