What is the Bacteria and How Perform Role to Develop Bacteria?

Bacteria are tiny organisms not visible to the human eye. Billions of bacteria live in and on people, animal and plants at all time. Many bacteria are helpful to us, but some of them are harmful and cause infection.
Commensals: 
               Are organisms that routinely colonize body surfaces without doing harm for example the bacteria normally present in the gastrointestinal tract. Pathogens: are organisms which are less commonly or never found as part of the normal flora, but they have the ability to colonize , thereby damaging the human host, either by direct invasion and injury or by the production of harmful toxic products. Man,s normal microbial flora protects him from invasion by other microbes. Minor changes in the environment may disturb the normal flora. Borad spectrum anitibiotics clear away commensals and permit overgrowth of resistant organisms whichare usually preent only in small numbers for example staphylococcal enterocolitis in patients given tetracyclines following gastric surgery and candida vaginitis following the use of ampicillin. Bacteria are different from other microorganisms and from higher plants and animals by differences in their cell structure.
      The cells of higher plants and animals have a distinc nucleus surrounded by a nuclear membrane. A cell with such a distinct nucleus is called eukaryotic cell or eukaryote. Bacterial cells have no distinct nucleus , but an area of nuclear material not surrounded by a nuclear membrane. A bacterial cell is called prokarytoic cell or prokaryote.In general , the structure and biochemical processess of prokaryotic cells are simpler than those of eukaryotic cells.
       The cell wall sturcture the outer covering of the bacterial cell. There are tow different types of cell wall. from grampositive and from gramnegative bacteria.
The functions, since the bacterial cell wall is rigid, it provides the cell with support, so that it can keep its shape.Without this rigid wall, the cell could burst from internal osmotic pressure.The cell membrane: the cell membrane is also called cytoplasmic membrane. It lies just beneath the cell wall and surrounds the cytoplasm of the cell.The cytoplasm: gel like substances that fills the inside of the cell, it contains the enzymes which catalyze the reactions taking place inside the cell and
make it possible for the cell to carry on its life process. withing the cytoplasm are ribosomes and the nuclear region.
 The nuclear region: an area that is composed of the genetic material, a single chromosome made up of DNA and associated proteins.The ribosomes:small particles in the cytoplasm and in the nuclear region of the bacterial cell.The capsule: gummy or gelatinuos coating over the surface of many bacteria. The glagella: tong appendages extending from the cell wall of many bacteria. the location of flagella is useful in identification of some species of bacteria.The pill:fine, hair, like appendages
extending from beneath the cell wall. they are muc hshorter and stiffer than the flagella.The spores:a non-growing form of some bacterial species. they are highly durable, protective packets containing all the essential parts of the cell,s protoplasm in condensed form.