13 May

Shape and Structure of Bacteria

The shape and structure of bacteria make it easy to identify them.  The structure of bacteria is simple.  They have supercoiled DNA in the cytoplasm and are able to carry out photosynthesis and respiration.  Their cell wall is made of a molecule called peptidogylan that is not found in any other kind of cell.  Bacteria range from .5 microns to 10 microns.  The shapes of bacteria can be grouped into three morphological types: rods (bacilli), cocci (spherical) and spirals or curved rods.  The rods or bacilli can have rounded, flat, or tapered ends and they can be motile or nonmotile.  Cocci may occur singly, in chains, in tetrad, or in irregular masses.  Most cocci are nonmotile because they lack flagella, the organelles of motility.  The spiral bacteria can exist as slender spirochaetes, as a spirillum, or as a comma-shaped curved rod (vibrio).