Thursday, December 28, 2006

cell membrane

Cell membranes provide adjustable barriers between the cell and the extracellular environment (ESF) or adjacent cells in eukaryotes. The membranes of cellular organelles provide functional compartmentalization from the cytosol. Thus, the cell itself is surrounded by the plasma membrane, and specific functional membranes form intracellular organelles (endoplasmic reticulum, Golgi apparatus) or isolate the contents of cellular organelles (endosomes, mitochondria) from the cytoplasm. art - cell membrane translucent :
art - cell membrane opaque :

Cell membranes are variably constituted of carbohydrates (adhesion and address loci), phospholipid bilayers (hydrophobic barriers), and proteins, which control permeability and cellular signalling. Peripheral membrane proteins are confined to the surfaces of membranes while integral membrane proteins are embedded in the membrane and may pass through the lipid bilayer one or more times.

Specialized membrane proteins function in cell adhesion (junctions) and as energy transducers, enzymes, ion channels, pumps, and receptors for neurotransmitters and hormones. Cell junctions utilize proteins that anchor cells together (desmosomes), that occlude passage of water between cells (tight junctions), and that permit direct communication between cells (gap junctions). diagram . desmosome : tem_desmosome : art - tight junction zonula adherens desmosome gap : diagram . tight junction : diagram . gap junction

ball-stick - globular proteins in phospholipid bilayer : ball-stick - carrier proteins : ball-stick - marker protein : ball-stick - marker proteins : ball-stick - receptor proteins : ball-stick - ion channel proteins: animation - carrier proteins : animation - receptor protein : animation - cholesterol

Main page of Cell : energy transducers : ion channels : pumps : receptors : Main page of Cell to Cell : cellular signalling : GPCRs : GPCR families : Mechanism For Degradation Of G Proteins : neurotransmission : Main page of BioChemistry : enzymes : lipids : neurotransmitters : proteins : phospholipids : receptors : Main page of Molecules : Main page of Pathways: Main page of Genes : Main page of Neuron: synapse :


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