How does archaea reproduce

The information below was adapted from OpenStax Biology Prokaryotes have been and are able to live in every environment by using whatever energy and carbon sources are available. Prokaryotes fill many niches on Earth, including being involved in nutrient cycles such as nitrogen and carbon cycles, decomposing dead organisms, and thriving inside living organisms, including humans. The very broad range of environments that prokaryotes occupy is possible because they have diverse metabolic processes.

Phototrophs or phototrophic organisms obtain their energy from sunlight. Chemotrophs or chemosynthetic organisms obtain their energy from chemical compounds. Prokaryotes not only can use different sources of energy but also different sources of carbon compounds.

Recall that organisms that are able to fix inorganic carbon for example, carbon dioxide into organic carbon for example, glucose are called autotrophs. In contrast, heterotrophs must obtain carbon from organic compounds. The terms that describe how prokaryotes obtain energy and carbon can be combined.

Thus, photoautotrophs use energy from sunlight, and carbon from carbon dioxide and water, whereas chemoheterotrophs obtain energy and carbon from an organic chemical source. Chemoautotrophs obtain their energy from inorganic compounds, and they build their complex molecules from carbon dioxide.

Finally, photoheterotrophs use light as an energy source, but require an organic carbon source they cannot fix carbon dioxide into organic carbon.

In contrast to the great metabolic diversity of prokaryotes, eukaryotes are only photoautotrophs plants and some protists or chemoheterotrophs animals, fungi, and some protists. The table below summarizes carbon and energy sources in prokaryotes. The videos below provide more detailed overviews of Archaea and Bacteria, including general features and metabolic diversity:. In fact, Archaea and Eukarya form a monophyletic group, not Archaea and Bacteria.

These relationships indicate that archaea are more closely related to eukaryotes than to bacteria, even though superficially archaea appear to be much more similar to bacteria than eukaryotes. This explains various genetic similarities but runs into difficulties when it comes to explaining cell structure. Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely-related to those of eukaryotes, notably the enzymes involved in transcription and translation.

Archaea exhibit a great variety of chemical reactions in their metabolism and use many sources of energy. These reactions are classified into nutritional groups, depending on energy and carbon sources. Some archaea obtain energy from inorganic compounds such as sulfur or ammonia they are lithotrophs.

These include nitrifiers, methanogens and anaerobic methane oxidisers. One compound acts as an electron donor and another as an electron acceptor. The energy released generates adenosine triphosphate ATP through chemiosmosis, in the same basic process that happens in the mitochondrion of eukaryotic cells.

The chromosomes replicate from multiple starting-points origins of replication using DNA polymerases that resemble the equivalent eukaryotic enzymes. However, the proteins that direct cell division, such as the protein FtsZ, which forms a contracting ring around the cell, and the components of the septum that is constructed across the center of the cell, are similar to their bacterial equivalents.

Privacy Policy. Skip to main content. Microbial Genetics. Search for:. Archaeal Genetics. Learning Objectives Describe the characteristics of Archaeal chromosomes and their replication. The circular chromosomes of archaea contain multiple origins of replication for initiation of DNA synthesis. Key Terms chromosome : A structure in the cell nucleus that contains DNA, histone protein, and other structural proteins. Learning Objectives Describe the evidence for the evolution of the Archaea from Bacteria.

No archaea are known to use photosynthesis. Phototrophic archaea use the sun's energy to produce chemical energy in the form of ATP. In the Halobacteria , light-activated ion pumps like bacteriorhodopsin produce ion gradients by pumping ions out of the cell through the plasma membrane.

The energy stored in such electrochemical gradients is subsequently converted into ATP by ATP synthase in a process that is a form of photophosphorylation. The ability of these light-driven pumps to transport ions across membranes depends on sunlight-driven alterations in the structure of a retinol cofactor embedded in the protein center.

Some swamp-dwelling archaea thrive in anaerobic settings; in fact, this primitive form of metabolism may have powered the first free-living organism. Such methanogenic metabolism relies upon carbon dioxide as an electron acceptor to oxidize hydrogen.

Methanogenesis invokes a gamut of coenzymes unique to these archaea, including coenzyme M and methanofuran. Sometimes various alcohols, and acetic or formic acid, are employed as methanogenic electron acceptors. These reactions are common in intestine-dwelling archaea. Acetic acid is also decomposed into methane and carbon dioxide by acetotrophic archaea.

These acetotrophs are archaea in the order Methanosarcinales, and are a major part of the ecological micro-organism communities that produce biogas. Atmospheric carbon is another source of energy input for autotrophic archaea who emply carbon fixation.

Having no cell nucleus, archaea do not reproduce via mitosis; rather, they procreate using a process called binary fission. In this binary fission process, archaeal DNA replicates, and the two strands are pulled apart as the cell grows. In some cases more than two daughter chromosomes can be created and subsequently pull apart, in a process called multiple fission. Archael chromosomes replicate from multiple origins of replication, using DNA polymerases that resemble counterpart eukaryotic enzymes.

However, the proteins that direct cell division, such as the protein FtsZ, that forms a contracting ring around the cell, and the components of the septum constructed across the center of the cell, resemble their bacterial likenesses.

Onyenwoke et al. It was first thought that most archaea were extremophiles, existing at the environmental limits of abiotic factor ranges.

Recently, it has been found that there are numerous archaea living in a broad range of habitats and environmental conditions. Some Haloarchaea undergo phenotypic switching and grow as several different cell types, including thick-walled structures that are highly resistant to osmotic shock.

These thickened walls permit survival under hyposaline low salt circumstances, but these alternative phenotypes are not actual reproductive structures—rather, they may assist the archaea in reaching new habitats. Indeed, some archaea thrive in extreme temperatures, often above degrees C; for example, they occur in hotsprings , geysers , black smokers, and oil wells.

Other viable environments include very cold environments and highly saline, acidic, or alkaline media. For example, Picrophilus torridus, an extreme archaean acidophile, thrives at pH of essentially zero, equivalent to a 1. Archaea are also found in very cold ocean environments, including polar seas. Many archaea also occur throughout the world's oceans among plankton communities as part of the picoplankton. Moreover, archaea include mesophiles that grow in mild conditions, in marshes, sewage, the oceans, and soils.

Halophiles, including the genus Halobacterium , survive in hypersaline environments such as salt lakes, and can outcompete bacterial counterparts at salinities greater than 20 percent.

This article was adapted from the Encyclopedia of Earth. In: Encyclopedia of Earth. Cutler J. Cleveland Washington, D.