Bacteria grow and reproduce outside or within a body and cause infections .They grow and multiply rapidly and make us ill.Soem common infections caused by bacteria are mouth sore, tooth decay, ear infection, cholera, typhoid, food poisoning and pneumonia.
Bacteria are prokaryotic organisms that reproduce asexually. Bacterial reproduction most commonly occurs by a kind of cell division called binary fission. Binary fission involves the division of a single cell, which results in the formation of two cells that are genetically identical. In order to grasp the process of binary fission, it is helpful to understand bacterial cell structure.
Bacterial Cell Structure
Bacteria have varying cell shapes. The most common bacteria cell shapes are spherical, rod-shaped, and spiral. Bacterial cells typically contain the following structures: a cell wall, cell membrane, cytoplasm, ribosomes, plasmids, flagella, and a nucleoid region.
Cell Wall: An outer covering of the cell that protects the bacterial cell and gives it shape.
Cytoplasm: A gel-like substance composed mainly of water that also contains enzymes, salts, cell components, and various organic molecules.
Cell Membrane or Plasma Membrane: Surrounds the cell's cytoplasm and regulates the flow of substances in and out of the cell.
Flagella: Long, whip-like protrusion that aids in cellular locomotion.
Ribosomes: Cell structures responsible for protein production.
Plasmids: Gene carrying, circular DNA structures that are not involved in reproduction.
Nucleoid Region: Area of the cytoplasm that contains the single bacterial DNA molecule.
Binary Fission
Most bacteria, including Salmonella and E.coli, reproduce by binary fission. During this type of asexual reproduction, the single DNA molecule replicates and both copies attach, at different points, to the cell membrane. As the cell begins to grow and elongate, the distance between the two DNA molecules increases. Once the bacterium just about doubles its original size, the cell membrane begins to pinch inward at the center. Finally, a cell wall forms which separates the two DNA molecules and divides the original cell into two identical daughter cells.
There are a number of benefits associated with reproduction through binary fission. A single bacterium is able to reproduce in high numbers at a rapid rate. Under optimum conditions, some bacteria can double their population numbers in a matter of minutes or hours. Another benefit is that no time is wasted searching for a mate since reproduction is asexual. In addition, the daughter cells resulting from binary fission are identical to the original cell. This means that they are well suited for life in their environment.