Polar (hydrophylic) heads on outside, non-polar (hydrophobic) tails on inside.Proteins: The variety of Life!StructureAmino acidsAlpha carbon and R groupsProteins: StructurePeptide bonds (amide bond – covalent – high energy)Amino end (N-terminus), Carboxyl end (C-terminus)Proteins: Levels of StructureFour levels of protein structure:Primary (a), Secondary (b), Tertiary (c), Quaternary (d)Membrane Proteins: the Workhorse of Neurons!Spanning (across) the lipid bilayerChannel ProteinsPolar R groups and nonpolar R groupsIon selectivity and gatingIon pumpsMovement across the Lipid Bilayer: ConcentrationDiffusionDissolved ions distribute evenlyIons flow down concentration gradient when:Channels permeable to specific ions are presentConcentration gradient across the membraneMovement across the Lipid Bilayer: Electrically charged particlesElectrical forcesElectrical force influences electrically charged ion movementElectrical conductance (g) and resistance (R); R = 1/gElectrical potential (Voltage - V)Flow of electrically charged particles/ions (Current – I)Omh’s law: I = gV or I = V/REquilibrium PotentialsEquilibrium Potential (Eion)No net movement of ions when separated by a phospholipid membraneEquilibrium reached when channels inserted into the phospholipid bilayerPoint at which voltage (electrical potential) difference exactly balances ionic concentration gradientIonic Equilibrium PotentialsEquilibrium Potentials for each ionsThe Nernst EquationUsed to calculates the exact value of the equilibrium potential for each ion in mV (millivolts)Takes into consideration:Charge of the ionTemperature (in absolute degrees!)Ratio of the external and internal ion concentrationsThe Ionic Basis of The Resting Membrane PotentialThe Nernst Equation:Eion = 2.303 RT log [ion]ozF [ion]iThe Ionic Basis of The Resting Membrane PotentialThe Distribution of Ions Across the MembraneK+ more concentrated on inside, Na+, Cl- and Ca2+ more concentrated outside, many negative proteins insideNRSC 2100 1st Edition Lecture 4The Phospholipid MembraneBilayer: Hydrophylic and hydrophobic Polar (hydrophylic) heads on outside, non-polar (hydrophobic) tails on inside.Proteins: The variety of Life! Structure• Amino acids• Alpha carbon and R groupsProteins: StructurePeptide bonds (amide bond – covalent – high energy)• Amino end (N-terminus), Carboxyl end (C-terminus)Proteins: Levels of Structure• Four levels of protein structure:• Primary (a), Secondary (b), Tertiary (c), Quaternary (d)Membrane Proteins: the Workhorse of Neurons!Spanning(across) the lipid bilayer– Channel Proteins• Polar R groups and nonpolar R groups• Ion selectivity and gating• Ion pumpsMovement across the Lipid Bilayer: ConcentrationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• Diffusion– Dissolved ions distribute evenly– Ions flow down concentration gradient when:• Channels permeable to specific ions are present• Concentration gradient across the membraneMovement across the Lipid Bilayer: Electrically charged particles• Electrical forces• Electrical force influences electrically charged ion movement• Electrical conductance (g) and resistance (R); R = 1/g• Electrical potential (Voltage - V)• Flow of electrically charged particles/ions (Current – I)• Omh’s law: I = gV or I = V/REquilibrium Potentials• Equilibrium Potential (Eion) – No net movement of ions when separated by a phospholipid membrane– Equilibrium reached when channels inserted into the phospholipid bilayer– Point at which voltage (electrical potential) difference exactly balances ionic concentration gradientIonic Equilibrium Potentials• Equilibrium Potentials for each ions– The Nernst Equation• Used to calculates the exact value of the equilibriumpotential for each ion in mV (millivolts) • Takes into consideration:– Charge of the ion– Temperature (in absolute degrees!)– Ratio of the external and internal ion concentrationsThe Ionic Basis of The RestingMembrane Potential The Nernst Equation:Eion = 2.303 RT log [ion]o zF [ion]iThe Ionic Basis of The Resting Membrane Potential • The Distribution of Ions Across the Membrane– K+ more concentrated on inside, Na+, Cl- and Ca2+ more concentrated outside, many negative proteins