what kind of studies would you do to prove a cell is archaea

Learning Objectives

• Draw the unique features of each category of Archaea
• Explain why archaea might not be associated with human microbiomes or pathology
• Give common examples of archaea commonly associated with unique environmental habitats

Like organisms in the domain Bacteria, organisms of the domain Archaea are all unicellular organisms. However, archaea differ structurally from bacteria in several significant ways, every bit discussed in Unique Characteristics of Prokaryotic Cells. To summarize:

• The archaeal cell membrane is composed of ether linkages with branched isoprene chains (as opposed to the bacterial cell membrane, which has ester linkages with unbranched fatty acids).
• Archaeal cell walls lack peptidoglycan, but some comprise a structurally similar substance chosen pseudopeptidoglycan or pseudomurein.
• The genomes of Archaea are larger and more circuitous than those of bacteria.

Domain Archaea is equally diverse as domain Bacteria, and its representatives can exist found in any habitat. Some archaea are mesophiles, and many are extremophiles, preferring extreme hot or cold, farthermost salinity, or other conditions that are hostile to almost other forms of life on earth. Their metabolism is adapted to the harsh environments, and they can perform methanogenesis, for instance, which bacteria and eukaryotes cannot.

The size and complication of the archaeal genome makes it difficult to allocate. Most taxonomists hold that within the Archaea, there are currently 5 major phyla: Crenarchaeota, Euryarchaeota, Korarchaeota, Nanoarchaeota, and Thaumarchaeota. There are likely many other archaeal groups that have not all the same been systematically studied and classified.

With few exceptions, archaea are not present in the human microbiota, and none are currently known to exist associated with infectious diseases in humans, animals, plants, or microorganisms. However, many play important roles in the environment and may thus accept an indirect bear upon on human health.

Crenarchaeota

Crenarchaeota is a class of Archaea that is extremely various, containing genera and species that differ vastly in their morphology and requirements for growth. All Crenarchaeota are aquatic organisms, and they are thought to be the most abundant microorganisms in the oceans. Most, but not all, Crenarchaeota are hyperthermophiles; some of them (notably, the genus Pyrolobus) are able to grow at temperatures up to 113 °C.^[1]

Effigy one. Sulfolobus, an archaeon of the course Crenarchaeota, oxidizes sulfur and stores sulfuric acid in its granules.

Archaea of the genus Sulfolobus (Figure ane) are thermophiles that adopt temperatures around 70–80°C and acidophiles that prefer a pH of ii–three.^[ii] Sulfolobus can alive in aerobic or anaerobic environments. In the presence of oxygen, Sulfolobus spp. use metabolic processes like to those of heterotrophs. In anaerobic environments, they oxidize sulfur to produce sulfuric acrid, which is stored in granules. Sulfolobus spp. are used in biotechnology for the production of thermostable and acrid-resistant proteins chosen affitins.^[three] Affitins tin can bind and neutralize various antigens (molecules found in toxins or infectious agents that provoke an immune response from the body).

Another genus, Thermoproteus , is represented by strictly anaerobic organisms with an optimal growth temperature of 85 °C. They accept flagella and, therefore, are motile. Thermoproteus has a cellular membrane in which lipids form a monolayer rather than a bilayer, which is typical for archaea. Its metabolism is autotrophic. To synthesize ATP, Thermoproteus spp. reduce sulfur or molecular hydrogen and apply carbon dioxide or carbon monoxide every bit a source of carbon. Thermoproteus is thought to be the deepest-branching genus of Archaea, and thus is a living example of some of our planet's earliest forms of life.

Think almost It

• What types of environments do Crenarchaeota prefer?

Euryarchaeota

The phylum Euryarchaeota includes several distinct classes. Species in the classes Methanobacteria, Methanococci, and Methanomicrobia represent Archaea that tin be generally described every bit methanogens. Methanogens are unique in that they tin reduce carbon dioxide in the presence of hydrogen, producing methyl hydride. They tin live in the virtually extreme environments and can reproduce at temperatures varying from below freezing to boiling. Methanogens have been constitute in hot springs as well every bit deep under water ice in Greenland. Some scientists have even hypothesized that methanogens may inhabit the planet Mars because the mixture of gases produced by methanogens resembles the makeup of the Martian temper.^[iv]

Methanogens are thought to contribute to the formation of anoxic sediments past producing hydrogen sulfide, making "marsh gas." They also produce gases in ruminants and humans. Some genera of methanogens, notably Methanosarcina , tin grow and produce methane in the presence of oxygen, although the vast bulk are strict anaerobes.

The class Halobacteria (which was named earlier scientists recognized the distinction betwixt Archaea and Bacteria) includes halophilic ("salt-loving") archaea. Halobacteria require a very high concentrations of sodium chloride in their aquatic environs. The required concentration is close to saturation, at 36%; such environments include the Dead Body of water as well as some salty lakes in Antarctica and south-central Asia. One remarkable characteristic of these organisms is that they perform photosynthesis using the protein bacteriorhodopsin, which gives them, and the bodies of water they inhabit, a beautiful purple color (Figure 2).

Figure 2. Halobacteria growing in these salt ponds gives them a distinct imperial color. (credit: modification of work past Tony Hisgett)

Notable species of Halobacteria include Halobacterium salinarum , which may exist the oldest living organism on earth; scientists accept isolated its DNA from fossils that are 250 one thousand thousand years one-time.^[5] Another species, Haloferax volcanii , shows a very sophisticated system of ion exchange, which enables it to balance the concentration of salts at high temperatures.

Retrieve about Information technology

• Where do Halobacteria live?

Finding a Link Between Archaea and Disease

Archaea are not known to crusade whatsoever illness in humans, animals, plants, bacteria, or in other archaea. Although this makes sense for the extremophiles, not all archaea live in extreme environments. Many genera and species of Archaea are mesophiles, so they tin can live in human and beast microbiomes, although they rarely practise. Equally nosotros have learned, some methanogens exist in the homo alimentary canal. Yet we have no reliable bear witness pointing to any archaean as the causative agent of whatever human disease.

Still, scientists have attempted to notice links between human disease and archaea. For example, in 2004, Lepp et al. presented evidence that an archaean called Methanobrevibacter oralis inhabits the gums of patients with periodontal affliction. The authors suggested that the activity of these methanogens causes the affliction.^[6] However, it was subsequently shown that there was no causal relationship between Grand. oralis and periodontitis. It seems more than likely that periodontal disease causes an enlargement of anaerobic regions in the mouth that are subsequently populated past G. oralis.^[7]

In that location remains no good answer equally to why archaea do not seem to be pathogenic, but scientists continue to speculate and hope to find the answer.

Key Concepts and Summary

• Archaea are unicellular, prokaryotic microorganisms that differ from bacteria in their genetics, biochemistry, and ecology.
• Some archaea are extremophiles, living in environments with extremely high or low temperatures, or extreme salinity.
• Only archaea are known to produce methane. Methane-producing archaea are chosen methanogens.
• Halophilic archaea prefer a concentration of salt close to saturation and perform photosynthesis using bacteriorhodopsin.
• Some archaea, based on fossil prove, are amongst the oldest organisms on earth.
• Archaea practise non alive in great numbers in homo microbiomes and are not known to cause illness.

Multiple Pick

Archaea and Leaner are most similar in terms of their ________.

1. genetics
2. cell wall construction
3. ecology
4. unicellular construction

Bear witness Respond

Reply d. Archaea and Bacteria are most similar in terms of their unicellular structure.

Which of the following is true of archaea that produce marsh gas?

1. They reduce carbon dioxide in the presence of nitrogen.
2. They live in the near extreme environments.
3. They are always anaerobes.
4. They accept been discovered on Mars.

Show Answer

Answer b. They live in the virtually extreme environments.

Fill in the Blank

________ is a genus of Archaea. Its optimal environmental temperature ranges from 70 °C to 80 °C, and its optimal pH is 2–3. It oxidizes sulfur and produces sulfuric acid.

Show Answer

Sulfolobus is a genus of Archaea. Its optimal environmental temperature ranges from 70 °C to eighty °C, and its optimal pH is 2–three. It oxidizes sulfur and produces sulfuric acid.

________ was one time thought to be the cause of periodontal disease, but, more recently, the causal relationship between this archaean and the disease was not confirmed.

Show Respond

Methanobrevibacter oralis was once thought to be the cause of periodontal disease, only, more recently, the causal relationship between this archaean and the affliction was not confirmed.

Call back about It

1. What accounts for the purple color in salt ponds inhabited past halophilic archaea?
2. What prove supports the hypothesis that some archaea live on Mars?
3. What is the connection between this methane bog and archaea?

(credit: Chad Skeers)

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Source: https://courses.lumenlearning.com/microbiology/chapter/archaea/

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