Search results
Results from the WOW.Com Content Network
Structures found on meteorite fragment Allan Hills 84001. Nanobacterium (/ ˌ n æ n oʊ b æ k ˈ t ɪər i əm / NAN-oh-bak-TEER-ee-əm, pl. nanobacteria / ˌ n æ n oʊ b æ k ˈ t ɪər i ə / NAN-oh-bak-TEER-ee-ə) is the unit or member name of a former proposed class of living organisms, specifically cell-walled microorganisms, now discredited, with a size much smaller than the generally ...
Structures found in the ALH84001 meteorite are similar to the structures found in nanobes Not to be confused with Nanobacteria or Ultramicrobacteria . A nanobe ( / ˈ n æ n oʊ b , ˈ n eɪ n oʊ b / ) [ 1 ] is a tiny filamental structure first found in some rocks and sediments .
Electron micrograph of the bacterium Pelagibacter ubique. Pelagibacter ubique is one of the smallest known free-living bacteria, with a length of 370 to 890 nm (0.00037 to 0.00089 mm) and an average cell diameter of 120 to 200 nm (0.00012 to 0.00020 mm).
A few are found as endosymbionts of animals. Although only a few centimetres thick at most, microbial mats create a wide range of internal chemical environments, and hence generally consist of layers of microorganisms that can feed on or at least tolerate the dominant chemicals at their level and which are usually of closely related species.
They are among the earliest creatures with bony heads. The microscopic layers of that shield appear to evolutionary biologists, "like they are composed of little tooth-like structures." [4] Neil Shubin writes: "Cut the bone of the [ostracoderm] skull open…pop it under a microscope and…you find virtually the same structure as in our teeth ...
The choanocytes (also known as "collared cells") of sponges (considered among the most basal metazoa) have the same basic structure as choanoflagellates. Collared cells are found in other animal groups, such as ribbon worms, [38] suggesting this was the morphology of their last common ancestor.
Microorganisms make up about 70% of the marine biomass. [4] A microorganism, or microbe, is a microscopic organism too small to be recognised adequately with the naked eye. In practice, that includes organisms smaller than about 0.1 mm. [12]: 13
Nitrogenase is inactivated by oxygen, so the heterocyst must create a microanaerobic environment. The heterocysts' unique structure and physiology require a global change in gene expression. For example, heterocysts: produce three additional cell walls, including one of glycolipid that forms a hydrophobic barrier to oxygen