Classification of Plants

Five Kingdoms of Classification

A General Study of Bacteria

Bacteria are the most primitive and diverse unicellular organisms found in living world. They are prokaryotic in nature as their genetic material, i.e. DNA, is not enclosed within a nuclear membrane. Because of their unique biochemical pathways and properties, they are of high economic importance to the human beings. Let us take a look at a general account of various features of bacteria.

Occurrence

• Bacteria are known to exist in almost every corner of the Earth.
• There are several thousands of bacteria in the air we breathe, water we drink and food we eat. In fact our own body is a home to various bacteria.
• Some species of bacteria are also found to inhabit some of the most unfavourable conditions on Earth, such as hot water springs, geothermal vents, acidic lakes, etc.

Size
Bacteria are the smallest living organisms, ranging from size 0.2 - 2.0 μm.

Shape
Bacteria are found in diverse shapes. On the basis of shape, they can be broadly classified as cocci (spherical bacteria), bacilli (rod-shaped bacteria), spirilla (spiral bacteria), and vibrio (comma-shaped bacteria).
 

• Bacterium is unicellular in nature, consisting of a cell wall made up of peptidoglycan, cell membrane and protoplast.
• The cytoplasm lacks any cell organelle, except vacuoles and ribosomes.
• DNA lies freely in the central region of the cytoplasm.
• In some cases, the cell wall is further surrounded by a slimy protective layer, called capsule.
• Some bacteria also con…