Membrane Structure & Function

Membrane Structure - Membrane Structure Function Chapter 5 Structure of a Biological Membrane The general structure of membranes is know as the

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Membrane Structure & Function Chapter 5
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Structure of a Biological Membrane The general structure of membranes is know as the fluid mosaic model . The phospholipid bilayer is like a “lake” in which a variety of proteins “float.” Phospholipid bilayer separates two aqueous regions
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Figure 5.1 The Fluid Mosaic Model
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Membrane Composition and Structure Cell membranes are bilayered, dynamic – Perform vital physiological roles – Form boundaries between cells and their environments – Regulate movement of molecules into and out of cells Lipids, proteins, and carbohydrates in various combinations make these tasks possible
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Membrane Composition and Structure All biological membranes contain proteins Many membrane proteins have hydrophilic and hydrophobic regions The association of protein molecules with lipid molecules is not covalent
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Membrane Composition and Structure Two types of membrane proteins: Integral membrane proteins span the bilayer (transmembrane) or are partially embedded in bilayer. Peripheral membrane proteins do not penetrate the bilayer.
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Membrane Composition and Structure
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Membrane Composition and Structure Some proteins are restricted in movement because they are anchored to components of the cytoskeleton or are trapped within regions of lipid rafts This causes an unequal distribution of proteins, allowing for specialization of certain regions of the cell membrane
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Membrane Composition and Structure Some cells have carbohydrates associated with their external surfaces Carbohydrate-bound lipid is called glycolipid Most of the carbohydrate in the membrane is covalently bonded to proteins, forming glycoproteins serve as recognition sites for other cells and molecules.
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Membrane Composition and Structure Two types of proteins may be in the membrane: – Integral proteins – Peripheral proteins These proteins function in: – Junctions – Channels and pumps – Chemical signals
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Cell-To-Cell junctions Allow the interaction between neighboring cells Three different types – Desmosomes – Tight junctions – Gap junctions
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Desmosomes Cells
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Tight Junctions • Push cells very close to each other to minimize space in between them • Prevents paracellular pathways Cells
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This note was uploaded on 02/11/2011 for the course LIFE SCIEN LS2 taught by Professor Soliman during the Spring '10 term at UCLA.

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Membrane Structure - Membrane Structure Function Chapter 5 Structure of a Biological Membrane The general structure of membranes is know as the

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