BIOC 3560 Study Guide - Final Guide: Spontaneous Process, Cytosol, Glycerol
3 Feb 2018
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Steroid hormones, o2 co2, n2, cholesterol based steroid hormones, most drugs are hydrophobic. Membranes have hydrophobic cores to prevent charged/polar compounds from entering cell. Acid/base situations involve nonpolar species to cross and enter the body (ex. Ionic compositions of cytosol are different from extracellular environment. Cytosol: more k+, less na+, less ca2+ There are ion concentration gradients across plasma membrane and across organelle membranes. Free energy of solution; g= go + rt ln c. G when molecules move from c1 (high) to c2 (low) If c1 > c2, ln (c2/c1(cid:895) is (cid:374)egative so g is negative because it is a spontaneous process. Diffusion occurs spontaneously from high to low concentrations c1 = c2 at equilibrium: transport of hydrophilic solutes, membrane channels. Rate of transport alpha [substrate] is not saturable. Gated; open and close in response to stimuli. Highly selective; allow one molecule to go across (ex. Aquaporins are water channels that are very fast that are constantly on.
