Extracellular materials

Extracellular material of a slimy or gelatinous nature is formed by many bacteria, especially those producing mucoid growths. This material may remain firmly adherent as a discrete covering layer on each cell, or it may part freely from the cells. In the former case it is known as a capsule in the latter, as free slime or gum. 

The basement membrane (BM) is a continuous layer of extracellular materials, forming a boundary between the basal layer of the epithelium and the connective tissues of the lamina propria and the submucosa. It can be subdivided into the lamina lucida,... 

In general, model discussions have proven to be very helpful in modern cell membrane research 60). Current membrane models — though perhaps oversimplified — are of high potential value for an understanding of important biological processes, e.g. intercellular communication, cell uptake of extracellular material, and transformation of external impulses into intracellular effects. 

Standard chemical fixation fails to preserve extracellular materials. In contrast, Os04-microwave heating or the high-pressure freezing-freeze-substitution technique is able to preserve such materials (Eggli and Graber, 1994). The former technique is simpler... 

Hobbie, J. E., and Lee, C. (1980) Microbial production of extracellular material importance in benthic ecology. In Marine Benthic Dynamics (Tenore, K., and Coull, B., eds.), pp. 341-346. Belle W. Baruch Institute for Marine Biology, University of South Carolina Press, Columbia. 

Lysosomes Membrane-lined vescicles containing hydolytic enzymes Involved in breakdown to intracellular and extracellular material... 

In subsequent chapters we analyze how the macromolecular components that are found in tissue give rise to the complex biological structures that make up the intracellular and extracellular materials. To do this we need to consider how stereochemistry of the units contained in macromolecules... 

Although sugar polymers are less abundant on a mass basis throughout vertebrate tissues they still are important components of the cell surface and extracellular materials. Unlike proteins that are made up of four basic struc-... 

Actin and tubulin are two important cellular components that are involved in cell shape and movement. Actin is present in all mammalian cells and is involved in cellular transport and phagocytosis (eating of extracellular materials), provides rigidity to cell membranes, and when bonded to tropomyosin and troponin, forms the thin filaments of muscle. Thbulin is the subunit from which microtubules are self-assembled. Microtubules are most commonly known for their role in cell division. The mechanisms of self-assembly of these macromolecules have been well studied and are important models of biological assembly processes. Below we examine each of these processes. 

All the above transport mechanisms are only applicable to the absorption of small molecules, less than approximately 500 Da. There is evidence that larger molecules can be absorbed with low efficiency due to endocy tosis. Endocy tosis is defined as the internalization of plasma membrane with concomitant engulfment of extracellular material and extracellular fluid. The process can be divided into two types, pinocytosis and phagocytosis. 

Additional isolation steps may be required for samples with high content of proteins, fat, polysaccharides or extracellular material. 

Biomass separation of insoluble from soluble material, with either phase being retained depending on the location of the product as intracellular or extracellular material. Examples of unit operations commonly used include centrifugation, filtration, and sedimentation. 

In a bioprocess the desired end product may be present as whole cells or intracellular or extracellular material at the end of a fermentation. Therefore in this first bioseparation stage, it may be necessary to recover either the solid or aqueous phase, with as much of the unwanted phase removed as possible, and with minimal loss of the desired material to maximize product yield. 

Bonkovsky HL, Blanchette PL, Schned AR. Severe liver injury due to phenelzine with unique hepatic deposition of extracellular material. Am J Med 1986 80(4) 689-92. 

Adsorptive) transcytosis a mechanism for transcellular transport in which a cell encloses extracellular material in an invagination of the cell membrane to form a vesicle, then moves the vesicle across the cell to eject the material through the opposite cell membrane by the reverse process. 

The basement membrane (BM) is a continuous layer of extracellular materials and forms a boundary between the basal layer of epithelium and the connective tissues of the lamina propria and the submucosa. The BM can be subdivided into the a) lamina lucida, b) lamina densa, and c) a sublayer of fibrous material. The functions of the BM include providing 1) adherence between epithelium and underlying connective tissues 2) mechanical support for epithelium and 3) a barrier to the passage of cells and some large molecules. 

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