The lipid is seen as a sea in which mainly monomeric proteins float unencumbered, and the bilayer surface is exposed directly to the aqueous environment. The model includes the ideas that the proteins of a membrane are dispersed, are at low concentration and that they match the hydrophobic dimension of an unperturbed lipid bilayer with peripheral belts of exposed hydrophobic side chains. As important and insightful as this model has been, the emergence of new findings during the passage of 33 years has weakened the generalizations it contains, and it is now appropriate to examine some of them more closely. 1a as it appears in virtually all biochemistry texts. The model has become the standard conceptualization of membrane architecture and is shown redrawn in Fig. To develop these themes fully would require a much longer text (perhaps a book?), so only representative references are given here, and use is made of the references in the longer treatments by the other authors.Īn influential step in the study of membranes was taken with the development by Singer and Nicholson in 1972 of the ‘fluid mosaic model’ 1, which pulled together findings and ideas from the preceding decade. To frame a context for the reviews that follow, a few general perspectives are presented briefly below. Further refinements led to the use of the barrier for its energy-storage properties and to the creation of ways to pass information between a cell and its environment. Thus, the lipid bilayer, which spontaneously forms permeability barriers surrounding aqueous interiors, must be modified by macromolecules for the uptake of nutrients and the disposal of waste. In the case of membranes, we might start with the origin of life, noting that compartmentalization is essential for an organism, and that with compartmentalization must come specific ways to surmount the barrier defining the boundary of the compartment - the membrane. The reductionist view of biology, to which many adhere, rests in part on the structure–function hypothesis: that the structures we find are there for specific functional reasons selected by evolution. Articles in this Insight expose current views of the importance, findings and concepts in membrane biology in some regions of the emerging landscape. This is leading to a great expansion of interest in the area. But now we have a rising number of high-resolution structures, an abundance of functional data and an evolving conceptual basis for framing more pointed questions. Most methods require purification and observation in aqueous environments alien to the molecular design of a membrane, and so the field had to rely on oversimplified views that still dominate the texts and teaching in this area. Perhaps this is understandable in view of the technical hurdles that working with them presents. He now produces Connect the World with Becky Anderson.Given their biological importance, membranes have been surprisingly neglected by biochemists until recently. In early 2013 he began a new role producing CNN International's Global Exchange in Abu Dhabi. He joined CNN International in Hong Kong, where he worked behind the scenes on World Business Today and News Stream, regularly contributing features and commentary to the latter's popular blog. He was also a regular presenter of short bulletins for East Central Scotland and the rest of the region. His reporting work encompassed hard news, sport and lighter feature stories for STV News as well as occasional political items for Politics Now. Prior to becoming a journalist, he was a Marketing Manager with VisitScotland, the national tourism agency. He formerly worked at ITV Border and later STV Central. Nicol Nicolson is a Scottish broadcast journalist.
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