A Basic Guide to Archaea

Archaea are single celled organisms that are fairly simple in nature. Archaea are considered prokaryotes because they do not contain a nucleus. This is one of many traits that they share with bacteria. Originally, in fact, archaea were actually believed to be a type bacteria and were not classified as a fully separate group until the late 1970s.

Archaea are often found in harsh conditions and were thought until recently to be made up entirely of extremeophiles, or organisms that thrive in and even sometimes require extreme conditions. As time has passed, however, scientists have found that while a majority of archaea can be classified this way, many archaea exist in far less extreme environments.

One trait that sets the archaea apart from bacteria is that not all archaea are enclosed in cell walls. Those that do have cell walls can be easily separated from bacteria because the walls lack peptidoglycan. Peptidoglycan is a carbohydrate and protein complex that makes up the cell walls of all bacteria. Another distinguishing feature is that archaea do not react to antibiotics in the same way that bacteria do.

Types of archaea can be quite diverse. Some archaea exhibit very unconventional morphology. Not all reproduce by binary fission, or the division of one cell into two new matching cells, instead they reproduce by fragmentation or budding. None, however, are known to produce spores for reproduction. Some are halophiles which survive and even thrive in high concentrations of salt, while others thrive in exceptionally hot areas. The planet's oceans contain a considerably large number of archaea and some of these are found near hydrothermal vents.

Archaea can be mobile by means of flagella which are structures made of protein along the outside of the cell. This is a trait they share with bacteria but the flagella of the archaea are very different in nature from that of bacteria.

Archaea also range wildly in the way they get nutrition or use energy. However, no archaea are currently known to use photosynthesis. The genes and enzymes of archaea are quite different from that of bacteria and often more closely resemble those of multicellular organisms.