Bacteria

Bacetria are prokaryotic organisms and probably the most common form of life on Earth. Some are pathogenic, but the majority do no harm and are beneficial.

All bacteria cells have some features in common. All bacteria cells have a cell wall, the contents of which are usually hypertonic to the medium aroundthem. The cell wall prevents the cell swelling and bursting. It also maintains the shape of the bacterium, and gives support and protection to the contents of the cell. The cell surface membrane is similar in both structure and function to the membrane of eukaryotic cells. However bacteria have no mitrochondria so the cell membrane is also the site of some of the repiratory enzymes. In some bacterial cells the membrane shows infoldings known as mesosomes. Some bacteria have a capusle around their cell walls. This may be formed from starch, gelatin, protein or glycolipid, and protects the bacterium from phagocytosis by white blood cells…