The prokaryotes are the oldest and most abundant group of organisms on earth, and are the smallest unicellular organisms. There are certain factors that account for the success of prokaryotes such that they are able to withstand harsh environments and they are able to adapt to face the conditions that they are in.
One factor that accounts for the success of the prokaryotes is their way to survive. When environmental conditions are unfavorable, the bacterium becomes inactive. Some species of bacteria form endospores. An endospore is a thick wall that surrounds the genetic material while the rest of the cell disintegrates. The endospore does not reproduce or show any signs of life. It is similar to a seed. What is important about these endospores is that they can withstand harsh environmental conditions, such as boiling, freezing, and drying out. When the existing conditions then become favorable, the endospore germinates and in turn forms an active cell. This method of survival allows prokaryotes to last longer and allow them to germinate.
Another factor that accounts for the success of prokaryotes is their ability to metabolize most nitrogenous compounds. Nitrogen is essential in the synthesis of proteins and nucleic acids. Prokaryotes are successful because they can convert ammonia to nitrates. Others can convert atmospheric nitrogen to ammonia. This is known as nitrogen fixation. Some bacteria can even survive on light, carbon dioxide, atmospheric nitrogen, water, and minerals to survive. This means they are self-sufficient, and that is why prokaryotes are successful.
Three hostile environments in which prokaryotes survive are swamps, salt ponds, and hot springs. The classifications of the prokaryotes that live in these environments are archaebacteria. Methanogens are able to survive in swamps, extreme halophiles are able to survive in salt ponds, and thermoacidophiles are able to live in Hot Springs.
Methanogens are obligate anaerobes, this means that they cannot live in the presence of oxygen. To adapt to their homes in swamps and marshes they use elemental hydrogen to reduce carbon dioxide into methane. Extreme Halophiles are able to adapt to salt ponds because they can absorb it. That is why they live in high salinity environments. They are able to this by bacteriorhodopsin, which turns their pigment pink. Thermoacidophiles need an environment that is both hot (60 to 80 degrees Celsius) and acidic (2 to 4 pH). They can withstand this because they have no cell wall and can grow aerobically and anaerobically. That is how prokaryotes are able to adapt.
Prokaryotes are the oldest and most abundant group of organisms on earth because they are able to survive, adapt, and are self-sufficient.