Question

many members of the archaea have adapted to living in diverse habitats. discuss this in terms of their cell walls and membranes, as well as metabolism

Answer 1

Ans.

• Archea are the single celled organisms which have several unique molecular features, that differentiate them from the bacteria and eukaryotes.
• It occupies one of the domain in the basic all-life classification system.
• They form a major part of life on earth and are present in almost all of the organism's microbiota.
• Their distinctive morphological, geographical and metabolic features allow them to play several role in multiple eco-systems.
• In almost every habitat including, soil, oceans, and marshlands, their presence can be detected.

Cell walls and membranes of archaea ;

• Most of the archaea has a cell wall that is assembled from a surface layer proteins, forming an S-layer.
• This S-layer accounts for the chemical and physical protection of archaea in multiple stressful habitats and prevent contact of macromolecules with the membrane.
• Peptidoglycan is absent from the cell wall of archaea, making them susceptible to the enzymatic actions.
• Archaella are the archaeal flagella which are made up by the addition of subunits at the base and helps in their movement and rotation.
• Cell membranes of archaea are composed of glycerol-ether lipids, different from bacteria and eukaryotes, whose membranes consist of glycerol-ester lipids.
• This unique feature of archaeal cell membrane provide them ability to survive in environment of extreme stress on cells like increased heat and salinity.
• Enzymes required for the synthesis of phospholipid in archaea are different then bacteria and eukryots, thus ensuring their survival in th conditions harsh to other living organisms.
• The isoprenoid chain, associated with several cyclopropane or cyclohexane rings, form the lipid tail in archaea, which prevent leaking of their membranes at higher temperature.
• In several members of archaea, such as Ferroplasma, a monolayer replace the bilayer of lipid, making them rigid and more efficient in handling rigid environmental conditions such as highly acidic habitat.

Metabolism in archaea.

• Many chemical reactions participates in the metabolism of archaea and multiple energy sources are being utilized for the purpose depending upon the environmental conditions.
• Several members of archaea such as nitrifiers and methanogens uses inorganic compounds for the energy production.
• Several phototropic archaea uses sunlight for the energy generation.
• Methanogens archaea are the methane producing archaea, that lives in anaerobic conditions such as swamp,
• Use of carbon dioxide as an electron acceptor is a common reaction for the oxidation of hydrogen in these archaea.
• Several coenzymes, like coenzyme M and methanofuran, are unique to methanogens archaea catalysing the carbon dioxide reaction mentioned.
• Methane producing archaea play key role of providing energy to those organisms which derive their nutrition from methane's oxidation.
• Phototrophic archaea produce ATP as an energy source by using the sun light.
• In some archaea, light activated ion pumps create ion gradients and energy of these gradients is transformed by ATP synthase into ATP, similar to the process of phosphorylation.
• Such diverse metabolic pathways help them survive in multiple habitats and harsh environmental situations.