Mononucleus - Bacteria

The smallest living things on earth are the prokaryotic cells. Bacteria fall into the Monera Kingdom. They have a single DNA molecule in the cytoplasm. Almost all monerans have a cell wall that protects the cell and gives it its shape. Some monerans have a layer outside the cell wall called the capsule. This helps the cell cling to surfaces.
A typical bacterium is about 2 micrometers long. Inside the cell, there are nucleic acids, enzymes, and other substances necessary to carry out the cells life process.
Bacterium have long , thin, hairlike structures called flagella. They act as a propeller, as they rotate and move in response to chemical stimulation. Some have strands of pili , which enables them to stick itself to a surface.
Some shell shapes important in classifying monera are: spherical cells, called cocci ; Rod shaped cells called bacilli, and spiral shaped cells called spirilli. There are over 16,000 species of monerans.
Bacteria Showing Flagella
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