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Typus
KomplettPlagiat
Bearbeiter
Klgn
Gesichtet
Yes
Untersuchte Arbeit:
Seite: 11, Zeilen: 1 ff. (entire page)
Quelle: Anézo 2003
Seite(n): 25, 26, Zeilen: 25:27-34, 26:1 ff
[The notions of integral and peripheral] membrane proteins were asserted and it was also suggested that some proteins might pass completely through the membrane.

The fluid mosaic model has constituted the most important step in the development of our current understanding of biomembranes. Although the model contains little structural detail, it summarizes the essential features of biological membranes. This model has undergone modifications and refinements are still expected in the future. In particular, it is now clear that membrane proteins do not all diffuse freely in the plane of the bilayers – their mobility varies in morphologically distinct membranes from highly mobile arrangements to rigid structures whose molecular motion is more or less constrained. The existence of differentiated lateral domains within the membrane is also now known. Some regions of biological membranes are not arranged in the traditional bilayers; hexagonal or cubic phases, for instance, may also occur. Nevertheless, the fluid mosaic model still provides the conceptual backdrop for all current models, which just represent refined versions.

I.1.3 Model membranes

Various model membrane systems have been developed for studying biomembrane properties. The simplest model systems are provided by pure lipids or lipid mixtures, forming a bilayers. Since these systems do not contain membrane proteins and usually exhibit a simple lipid composition, they are not able to reproduce all the properties found in real membranes but the main biophysical and biochemical features are nevertheless preserved. More complex systems reconstitute lipid-protein mixtures and provide insight into lipid-protein interactions.

Liposomes are probably the most commonly used model membrane systems. The term “liposome” refers to any lipid bilayer structure, which encloses a volume. The primary uses of liposomes are to encapsulate solutes for transport studies and to provide model membranes in which proteins can be incorporated. Multilamellar vesicles (MLV) were the first liposomes to be characterized and consist of multiple bilayers forming a series of concentric shells with a diameter ranging from 5 to 50 μm. MLV are easy to [prepare, can be made in large quantities and high concentrations, and exhibit reproducible properties.]

[page 25]

The notions of integral and peripheral membrane proteins were asserted and it was also suggested that some proteins may pass completely through the membrane.

The fluid mosaic model has constituted the most important step in the development of our current understanding of biomembranes. Although the model contains little structural detail, it summarizes the essential features of biological membranes. This model has undergone modifications and refinements are still expected in the future. In particular, it is now clear that membrane proteins do not all diffuse freely in the plane of the bilayer: their mobility varies

[page 26]

in morphologically distinct membranes from highly mobile arrangements to rigid structures whose molecular motion is more or less constrained. The existence of differentiated lateral domains within the membrane is also now known. Some regions of biological membranes are not arranged in the traditional bilayer; hexagonal or cubic phases, for instance, may also occur. Nevertheless, the fluid mosaic model still provides the conceptual backdrop for all current models which just represent refined versions.

1.1.6 Model membranes

Various model membrane systems have been developed for studying biomembrane properties. The simplest model systems are provided by pure lipids or lipid mixtures forming a bilayer. Since these systems do not contain membrane proteins and usually exhibit a simple lipid composition, they are not able to reproduce all the properties found in real membranes, but the main biophysical and biochemical features are nevertheless preserved. More complex systems reconstitute lipid-protein mixtures and provide insight into lipid-protein interactions.

Liposomes Liposomes are probably the most commonly used model membrane systems. The term “liposome” refers to any lipid bilayer structure which encloses a volume. The primary uses of liposomes are to encapsulate solutes for transport studies and to provide model membranes in which proteins can be incorporated. Multilamellar vesicles (MLV) were the first liposomes to be characterized and consist of multiple bilayers forming a series of concentric shells with a diameter ranging from 5 to 50 µm. MLV are easy to prepare, can be made in large quantities and high concentrations, and exhibit reproducible properties.

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