CYTOSKELETON — Until very recently, scientists thought that the shape of all bacteria was completely determined by the peptidoglycan layer (cell wall). Although this is true of many bacteria, particularly the cocci. — Other bacteria produce long polymers of a protein called Actin and Tubulin, arranged in helical ribbons around the cell just under the cell membrane. — These fibers contribute to cell shape, perhaps by influencing the way peptidoglycan is manufactured, and also function in cell division. — The fibers have been found in rod-shaped and spiral bacteria. — The Cytoskeleton provides support and shape and assists in transporting substances through the cell. Figure – 11.1: Bacterial cytoskeleton (The actin fibers in these rod-shaped bacteria are Fluorescently stained)