The cell coat of the amoeba provides an impermeable layer of protection via a series of tightly packed helical proteins protruding from the cell membrane.

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The amoeba is a relatively simple single-celled organism. Its internal structure consists of a few organelles that enable it to carry out all functions necessary for life in an aquatic environment. It is separated from its environment by a cellular membrane that usually includes a cell coat. The structure of the cell coat varies depending upon the species.

A specific genus of amoeba, Paradermamoeba, has been found to have an exceptionally thick and strong cell coat. The structure of this cell coat has been difficult to determine due to its relative impermeability. Only after partial digestion of the cell coat was it able to be properly visualized using an electron microscope, suggesting the cell coat is impenetrable to light.

The structure of the cell coat of Paradermamoeba is likely what gives it its strength and flexibility. The cell coat includes a network of regularly spaced, tightly packed, helical protrusions that have hollow, pentagonal, glass-shaped tips on their ends. It is believed that this is the structure that provides the amoeba with its impenetrable quality.

This summary was contributed by Alexis Dean.

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References

"The genus Paradermamoeba was established for a single species, Paradermamoeba valamo [1993]...Later a second species of this genus, P. levis, was discovered and described (Smirnov and Goodkov,1994). Amoebae of this genus have a very thick (up to 520 nm) cell coat, consisting of a layer of densely packed helical glycostyles with pentagonal glass-shaped tips. Perhaps, the impenetrability of the glycocalyx was the reason for numerous failed attempts to investigate the ultrastructure of these species." (Smirnov and Goodkov 2004:113)

"The cell coat of this species is about 520 nm of total thickness, and consists of a layer of regularly arranged tightly packed helical-shaped glycostyles. Coils of neighboring helices overlap. Each glycostyle terminates with a hollow straight funnel-shaped structure, which sometimes seems to be pentagonal in cross-section. The length of the spiral part of the glycostyles is about 400 nm and the diameter is about 100 nm; length of the straight terminal part of glycostyles is about 120 nm. Helices form 7-7,5 turns. They are embedded in an unstructured electron-transparent matrix which does not seem to prevent the neighboring glycostyles from moving in relation to each other." (Smirnov and Goodkov 1993:1)

[Note: The "impenetrability" appears to refer to the inability to determine the structure of the organism by using electron microscopy, which uses a beam of electrons to illuminate it.]

Journal article
Ultrastructure and geographic distribution of the genus Paradermamoeba (Gymnamoebia, Thecamoebidae)European Journal of ProtistologyAugust 24, 2004
Alexey Smirnov, Andrew Goodkov

Web page
Paradermamoeba valamo Smirnov & Goodkov 1993

Book section
Cellular Membranes of Amoeba

No link available.
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Living System/s

Organism
AmoebaSpecies

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