Lecture 3 Membrane Proteins Chapter Five Cell Membranes: Overview Cell structure &amp; support Barrier isolates cell (impermeable) Chemically Physically Regulates exchange (semipermeable) Cell communication Membrane Permeability Figure 5-6 Ion Transport Across the Cell Membrane Figure 5-9 - Overview Figure 5-4 <a href="/keyword/facilitated-diffusion/" >facilitated diffusion</a> Uses transport proteins Passive Diffusion to Equilibrium Figure 5- 21: Diffusion stops at equilibrium (panoramic lower left 66%) <a href="/keyword/facilitated-diffusion/" >facilitated diffusion</a> Carriers: Uniport and Co-Transport Figure 5-12 - Overview Figure 5-13b Primary Active Transport: ATP Dependent Primary Active Transport Figure 5-16 The Sodium-Potassium ATPase Pump Figure 5-17 - Overview Table 5-2 Secondary Active Transport Figure 5-18 - Overview Table 5-3 Channel Proteins: Channel properties Selectivity which ion flows through pore Conductance how fast ions can flow Gating open or closed Voltage Ligand Chemical Neurotransmitter Mechanical Deformation Figure 5-10 Figure 5-11 Channel Proteins: Gating Figure 5-9: Gating of channel proteins Voltage-gated channels: Voltage Gated Sodium Channels Sodium Channel Voltage-gated channels: S4 Forms Voltage Sensor Sodium Channel Voltage-gated channels: Components of Channel Sodium Voltage Gated Sodium Channel The Acetylcholine Receptor: A Ligand-Gated Channels: ACh ACh ACh ACh Ionotropic ACh, GABA, and Glycine Receptors SUBUNIT extracellular ACh intracellular M2 Figure 5-7 (3 of 3)