Membrane structure of cells

In biological systems molecular assemblies connected by non-covalent interactions are as common as biopolymers. Examples arc protein and DNA helices, enzyme-substrate and multienzyme complexes, bilayer lipid membranes (BLMs), and aggregates of biopolymers forming various aqueous gels, e.g, the eye lens. About 50% of the organic substances in humans are accounted for by the membrane structures of cells, which constitute the medium for the vast majority of biochemical reactions. Evidently organic synthesis should also develop tools to mimic the Structure and propertiesof biopolymer, biomembrane, and gel structures in aqueous media. 

Many of the physical changes in membrane structure of cells are reversible and species differences in the degree of disruption of dry membranes may relate to differences in composition, protective mechanisms or to additional damage occurring during desiccation (see below). 

DMAE can be incorporated into the membrane structure of cells, where its anti-oxidant properties improve... 

Clandinin MT, Cheema S, Field CJ, Garg ML, Venkatraman JT. Clandinin TR. Dietary fat exogenous determination of membrane structure of cell function. Fed Am Soc Exp Biol J 1991 5 2761-2769. 

Features Lipid which maintains membrane structure of cells... 

Uses An ether-type lipid which maintains membrane structure of cells and gives exc. emolliency to skin liq. crystal former emulsifier Regulatory JSCI listed Properties Wh. to pale yel. solid in liq. 

Properties Liq. dens. 0.924g/cm3 b.p. 470.6 C flash pt. 238.4 C Uses Liquid crystai former, emoiiient, and emulsifier in cosmetics Features Maintains membrane structure of cells Manuf./Distrib. Hangzhou Sage Chem. Nanjing Chemlin Trade Names Nikkoi Seiachyi Alcohol Senegal gum. See Acacia Septochol. See Desoxycholic acid Sesame amide propylbetaine. See Sesamidopropyl betaine Sesame fatty acid diethanolamide. See Sesamide DEA Sesame oil Sesame seed oil. See Sesame (Sesamum indicum) oil Sesame (Sesamum indicum) oil CAS 8008-74-0 EINECS/ELINCS 232-370-6... 

Singer, S. J., and Nicolson, G. L., 1972. The fluid mosaic model of the structure of cell membranes. Science 175 720-731. 

Gorter and Grendel in 1925 [527], drawing on the work of Langmuir, extracted lipids from RBC ghosts and formed monolayers. They discovered that the area of the monolayer was twice that of the calculated membrane surface of intact RBC, indicating the presence of a bilayer. This was the birth of the concept of a lipid bilayer as the fundamental structure of cell membranes (Fig. 7.1). 

Angersbach, A., Heinz, V., and Knorr, D. 2002. Evaluation of process induced dimensional changes in the membrane structure of biological cells using impedance measurement. Biotechnol. Progr. 18, 597-603. 

Fig. 4. A schematic illustration of the membrane structure of a hypothetical eukaryotic (animal) cell.

Finean, J.B. (1972). The development of ideas of membrane structure. Sub-Cell. Biochem. 1, 363-373. 

Membrane proteins (which make up approximately one-third of the total number of known proteins) are responsible for many of the important properties and functions of biological systems. They transport ions and molecules across the membrane they act as receptors and they have roles in the assembly, fusion, and structure of cells and viruses. Presently, investigating membrane proteins is one of the most difficult challenges in the area of structural biology and biophysical chemistry. Our knowledge of membrane proteins is limited, primarily because it is very difficult to crystallize these protein systems due to the extreme hydrophobic interactions between the proteins and the membrane. New methods are needed and current techniques need to be extended to study the structural properties of membrane proteins. 

Has detergent like action on cell membrane and have high affinity for phospholipids. They penetrate into and disrupt the structure of cell membranes,... 

The hepatocytes was subcultured for 2 days and their albumin secretion activity was measured. The TRS-harvested hepatocytes showed nearly the same albumin secretion activity as the primary culture, whereas the ERS-harvested ones showed only 20% activity. This finding is important because no subculture of hepatocyte has ever been successful, owing to a possible proteolytic disruption of cell-membrane structure (especially cell-cell adhesion) in the course of trypsin treatment. 

Lehninger, A. L. Metabolite carriers in mitochondrial membranes. In The Ca++ transport system in the dynamic structure of cell membranes, pp. 119. Wallach, D. F. H., Fisher, H. (eds.). New York, Heidelberg, Berlin Springer 1971... 

The dates of these references tell us about the current interest in this topic. However, despite the promising results obtained, and the great interest paid to this new alternative method, the mechanism of cell disruption is still unclear and the quantification of the technological process is not yet precise. Furthermore, it would be essential to understand the relationship between the degree of inactivation and the dimensions and the structure of cell membranes, and the shape of the micro-organism. 

The fluid-mosaic model for biological membranes as envisioned by Singer and Nicolson. Integral membrane proteins are embedded in the lipid bilayer peripheral proteins are attached more loosely to protruding regions of the integral proteins. The proteins are free to diffuse laterally or to rotate about an axis perpendicular to the plane of the membrane. For further information, see S. J. Singer and G. L. Nicolson, The fluid mosaic model of the structure of cell membranes, Science 175 720, 1972. 

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