BME 20100 Lecture Notes - Lecture 10: Membrane Transport, Membrane Potential, Thermodynamics
27 Nov 2017
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Document Summary
Rate proportional to magnitude of chemical gradient. Large and/or proteins polar molecules and ions. Types in eukaryotes: ion channels, aquaporins, transport proteins. Mechanosensitive channels - open in response local deformation in membrane. Ligand-gated channels - open in response to an extracellular chemical stimulus. Signal-gated channels - open on intracellularly binding of a signaling molecule (e. g. ca2+) Supports rapid and selective transport of k+ 10,000 times more permeable to k+ than. Approximately dimensioned for k+, filter narrows and is lined with carbonyl groups. Anionic side chains on cytoplasmic face attract cations. Type of prokaryotes: ionophores (carrier or channel-forming), porins. Carrier (nonpolar) - selectively bind ions followed by diffusion through membrane. Channel-forming - form transmembrane channels or pores through which ions can diffuse. Support passive diffusion in either direction, so their effect is to equilibrate the concentrations of their selected ions. Found in several bacterial strains and also.
