Prokaryotes are the organisms which have primitive nucleus. All bacteria are prokaryotes because they lack a distinct nucleus with nuclear membrane. The cytoplasm of prokaryotic cells lacks in well defined cell organelles such as endoplasmic reticulum, Golgi apparatus, Mitochondria,centrioles, nucleoli, cytoskeleton. The size of these cells range between 1 micrometre to 3 micrometres, so they are barely visible under the light microscope. Now let's moveon to diagram. 1.Draw a capsule shape which represents a basic structure of Bacilli bacterial cell. Draw two more lines over basic capsule shape which represents Cell wall. Place some dots inside it. 2. Draw one more outer covering with considerable thickness.This represents outer slimy Capsule. Draw some faint oblique lines within to highlight it. 3.Draw several Pili around the Prokaryotic cell as shown, Make a whip like flagellum at the bottom of the cell. Note: A bacterial cell may have more than one flagella but we draw only one for sake of simplicity. 4. Draw Mesosome originating from plasma membrane. 5.Label the parts as shown Cont:- The smallest bacterium is Dialister Pneumosintes (0.15 to 0.3 micrometers) and the largest is Spirillum volutans (13 to 15 micro meters) in length. The outer covering of bacterial cell comprises three layers: Plasma membrane, Cell wall and Capsule. The bacterial plasma membrane also provides a specific site at which the single circular chromosome remains attached. It is the point from where DNA replication starts. Infoldings of plasma membrane give rise to Mesosomes or chondrioids. They form coplex whorls of convoluted membranes, increasing surface area. In Photosynthetic bacteria, these infoldings also form Chromatophores bearing photosynthetic pigments. The bacterial cell wall is rigid chiefly composed of Murein or muramic acid, teichoic acids and teichuronic acids. In some bacteria cell wall is surrounded by an additional slime or gel layer called capsule. It is thick mucilaginous and is secreted by plasma membrane.It serves as protective layer against attack of Phagocytes and by viruses.
