also acts as the permeability barrier and contains a number of transport systems that selectively mediate the transfer of substance in and out of the cell.
Bacterial membranes are similar to those of eukaryotes except that they consist of saturated and monounsaturated fatty acids and do not contain sterols (Todar, 2005). Most bacteria have some kind of polysaccharide layer outside the cell wall or outer membrane, which is called the capsule or glycocalyx. Capsules, slime layers and glycocalyces mediate attachment to particular surfaces. Capsules also protect bacteria from engulfment by predatory protozoa or white blood cells and from
attack by antimicrobial agents or plant and animal origin. Capsules protect some bacteria from drying or dessication. Surface components are the way a prokaryote recognizes and makes contact with its environment.
The cytoplasmic component of bacteria consist of the prokaryotic chromosome and ribosomes. The chromosome is usually one large circular strand of DNA, free in the cytoplasm. Sometimes there are smaller pieces of DNA called plasmids. During cell growth and division, the prokaryotic chromosome is replicated in a semi-conservative fashion and distributed to the progeny cells. There may also be granular inclusions in the cytoplasm, e.g. glycogen, fat or phosphate reserves are stored as granules in the cytoplasm.
Some bacteria have a whip-like structure known as a flagellum which they use to propel themselves (Todar, 2005). Flagella are filamentous protein structures attached to the cell surface and rotate to provide motion to the bacterium. Other bacteria secrete a slime layer and ooze over surfaces, while still others remain stationary (Bacteria, 2005). Pili are short, stiff hairs on the surface of the bacteria which are used to help the bacteria adhere to surfaces. One, the sex pilus or F pilus, is used to mediate the transfer of DNA between bacteria when they mate.
M...