BIOL 1010 Lecture Notes - Lecture 4: Endoplasmic Reticulum, Lipid Bilayer, Golgi Apparatus
11 Oct 2018
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Is amphipathic meaning that it has a hydrophilic region and a hydrophobic region. Cholesterol (steroid): wedged between the phospholipid tails because it is also amphipathic (oh- group, at high temps: resists the motion of the membrane, at low temps: prevents the tails from becoming too rigid i. e. freezing. Integral: penetrates the cell membrane, through one leaflet or two, contains hydrophobic and hydrophilic regions (different amino acids) Peripheral: not embedded in the cell membrane, loosely bound to the surface of the membrane or the exposed parts of the integral proteins. On the cytoplasmic side of the cell, some membrane proteins are held in place through attachment to the cytoskeleton. On the extracellular side, certain membrane proteins are attached to fibres of the ecm. These attachments give the animal cells an even stronger framework than the plasma membrane alone could provide. Functions: transport, enzymatic activity, signal transduction (receptors), cell-cell recognition, intercellular joining, and attachment to the cytoskeleton and extracellular matrix (microfilaments etc. )
