Bacteria are single celled, microscopic organisms few micrometers in length. They do not have a membrane bound nucleus or membrane bound organelles such as the chloroplasts and the mitochondria. It does not contain steroids, cholesterol, mitosis or meiosis. The reproduction generally takes by asexual reproduction. Most of the bacteria's create a single spore when their supply of food runs low. The water gets removed from these spores leading to metabolism. These spores are very resistant to conditions like dryness.
Bacteria are an ancient form of life. Bacteria's have a wide number of shapes like rods, spheres or spirals, etc. Some of them are so small that they appear as little dots even under a light microscope; whereas some are large enough to be seen under the microscope having spectacular shapes.
Bacteria are present all around us. Under good growing conditions bacteria can grow in length or size slightly, a new cell wall grows at the center that forms two daughter cells each having the same genetic material as their parent cell. If they get a good environment, these two daughter cells get divided into four in just a period of 20 minutes. And eventually, it increases in the order of 1, 2, 4, 8, 16, 32, 64 ...
A cell membrane surrounds the bacterial cell that covers the contents of the cell and also acts as a barrier for holding the nutrients, proteins and other important components. They have very few intracellular structures. They do not have a membrane bound organelle in the cytoplasm as they are prokaryotes. They also lack mitochondria, nucleus, chloroplasts and other organelles such as the endoplasmic reticulum and the Golgi apparatus.
There is a bacterial cell wall at the outer end of the cell membrane. These walls are made of peptidoglycan that contains D-amino acids. This cell wall is very important for the bacteria to survive. Bacteria generally have two types of cell wall, Gram-positive and Gram-Negative. In some bacteria's, an S-layer arrayed protein molecules cover the outer side of the cell. This provides physical and chemical protection to the surface of the cell.
* Decomposition is one of the important roles played by the bacteria. It helps to decompose the remains of the dead plants and animals.
* Nitrogen fixation is also caused due to the bacteria. The nitrogen-fixing bacteria help by replacing the nitrogen in the soil for the green plants to thrive and flourish.
* Bacteria in our body help in the digestion of the food as well as for the production of vitamins. Dairy products like cheese, yogurt, butter milk, etc are prepared with the help of the bacteria.
Bacteria are present all around us. They play a very significant role in our day-to-day life. Many people frequently dismiss bacteria as germs, but don't forget that it is the bacteria that help us to breathe, produce vitamins and also maintain our atmosphere. Bacteria can be said as an eco-friendly organism.