BIOC 212 Lecture Notes - Lecture 5: Secretion, Secretory Protein, Membrane Lipids
29 Feb 2020
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Secretory pathway: transport system btw organelles & plasma membrane (pm) Proteins + lipids synthesis = er golgi pm. Internalization through endosomes degradation in lysosomes. Luminal environment ~ extracellular space (plasma) different from cytosol. Can store energy: [] gradients: voltage, ph, k, na, ca gradients. Membrane lipids: determine physical properties (mobility, curvature, thickness) Polar head groups: size + charge = effect on mobility. Classification by head groups: pc, pe, ps, sm, pi (can be phospho. ) Head group = sugar groups (many combinations) Interior = stronger negative charge (more ps) Lipid composition different btw organelles (biological requirements) Er & mitochondria = more pc & pe. Pm & trans-golgi have special microdomains: lipid rafts membrane. Longer tails + more cholesterol = straighter = thicker. Not permanent, can fuse and break apart. Transport of lipids: mechanism maintains lateral organization and asymmetry. Contact sites btw organelles (ex: er & mitochondria) On cytosolic side of smooth er membrane. Fatty acids (acyls) attached to coenzyme a:
