Transport of Molecules Across Selectively Permeable Membranes PDF

Transport of molecules across selectively permeable membrane Prepared by: Paul John L. Guzman, LPT Why is the movement of molecules vital in sustaining life?  The Fluid Mosaic Model  Membrane Lipids: The “FLUID” part of the model Phospholipids (Glyceropho...

Transport of molecules across selectively permeable membrane Prepared by: Paul John L. Guzman, LPT Why is the movement of molecules vital in sustaining life?  The Fluid Mosaic Model  Membrane Lipids: The “FLUID” part of the model Phospholipids (Glycerophospholipids)  Glycerophospholipids Glycerol + Phosphate Group + Fatty Acid chains Polar Head An AMPHIPATHIC/amphiphilic molecule Non- polar Tail  Diacylglycerol kinase OH Diacylglycerol Phosphoric Acid Phosphatidic Acid  The effect of chain length and degree of unsaturation of fatty acids on the fluidity of the plasma membrane  Membrane Proteins: The “MOSAIC” part of the model  PROTEINS polymers of amino acids (polypeptide)  Alpha Carbon Amino Carboxylic Group Acid Group Residue (Side chain) A Polypeptide is a string of amino acids bonded by peptide bond. Transport The ability of cells to move ions and molecules across membranes selectively What molecule with specific properties may pass the phospholipid bilayer?  Small Large *Considering transport proteins are Small NOT PRESENT Electrically Charged in the plasma membrane Through simple diffusion Hydrophobic (non-polar) Hydrophobic but the molecule is big Hydrophilic (polar) but the molecule is small and not charged Hydrophilic and the molecule is big Small ions  Examples Permeabili Factors More Less Permeable ty Ratio* Permeable Size: bilayer more permeable H2O H2N–CO–NH2 102:1 to smaller (Water) (Urea) molecules Polarity: bilayer CH3–CH2–CH2– HO–CH2–CHOH–CH2– more permeable OH OH 103:1 to non-polar molecules (Propanol) (Glycerol) Charge: bilayer O OH–(Hydroxide 9  Permeabili Factors More Less Permeable ty Ratio* Permeable Size: bilayer more permeable H2O H2N–CO–NH2 102:1 to smaller (Water) (Urea) molecules Polarity: bilayer CH3–CH2–CH2– HO–CH2–CHOH–CH2– more permeable OH OH 103:1 to non-polar molecules (Propanol) (Glycerol) Charge: bilayer highly O2 OH–(Hydroxide 109:1 impermeable to ions (Oxygen) ion) * Ratio of diffusion rate for the more permeable solute to the less permeable solute The movement of ions are determined by its *electrochemical gradient * Combination of electrical (electro) and concentration (chemical) gradient oute r Chemic inne al r gradien t Diffusion Facilitated Diffusion Resting Membrane Potential  Resting Membrane Potential  Molecules Cross Membranes by Simple Diffusion, Facilitated Diffusion, and Active Transport Transport across selectively permeable membrane Diffusion or Passive Transport Simple Diffusion Facilitated Diffusion Active Transport Bulk Transport  Simple Facilitated Diffusion Active Transport Diffusion The Font Size indicates the Concentration Gradient Simple Diffusion: Unassisted Movement Down the Gradient Simple Let’s react  Diffusion Molecules move Simple across a selectively Diffusion permeable membrane from an area of higher to lower concentration. It does not require Facilitated the input of energy Diffusion First Law of Thermodynamics (Law of Conservation of Energy) States that energy is neither created nor destroyed; moreover, it can only be transformed from one form to another. The total energy in the universe is constant. Energy is needed for movement  Diffusion Molecules move across Simple a selectively permeable Diffusion membrane from an area of higher to lower concentration. It does not require the input of metabolic Facilitated energy Diffusion Kinetic energy Diffusion always moves molecules toward equilibrium Diffusion  Diffusion (Osmosis) Osmolarity- relative total solute concentration inside or outside the cell Osmosis Diffusion of water across a selectively permeable membrane Movement of water from an area of higher water concentration to an area of lower water concentration across a selectively permeable membrane Movement of water from an area of lower solute concentration to an area of higher solute concentration across a selectively permeable membrane Movement of water from an area of higher water concentration (lower solute concentration) to an area of lower water concentration (higher solute concentration) across a selectively permeable membrane. Osmolarity- relative total solute concentration inside or outside the cell Facilitated Diffusion: Protein-Mediated Movement Down the Gradient  Simple Facilitated Diffusion Active Transport Diffusion The Font Size indicates the Concentration Gradient Facilitated Diffusion  Facilitated Diffusion Facilitated Molecules move across a selectively permeable membrane from an area of higher to lower concentration. through transport proteins It does not require the input of metabolic energy Kinetic energy  Transport Proteins Conformational Hydrophilic change channel Carrier(Transporters or Channel(Pores) Proteins Permeases) Proteins Carrier(Transporters or Channel(Pores) Proteins Permeases) Proteins Carrier Proteins Transport One or Two different kinds of Solutes Uniporter Symporter Antiporter Erythrocyte Three kinds of transmembrane protein channels: ion channels Porins Aquaporins K+ channel  Aquaporins (AQP): Transmembrane channel proteins that facilitate the Types Of Water Pollution Quiz. - ProProfs Quiz rapid passage of water Click me to know all aquaporins in the human body  ACTIVE TRANSPORT Protein-Mediated Movement Up the Gradient (against the concentration gradient)  Simple Facilitated Diffusion Active Transport Diffusion The Font Size indicates the Concentration Gradient  Acid Anhydride Bond High Energy Bond Phosphorylated Forms of Adenosine  Hydrolysis and Synthesis of ATP High Acid Anhydride Bond Energy Bond Energy is released  Active Transport Molecules move across a selectively permeable membrane from an area of lower to higher concentration through transport proteins It requires the input of metabolic energy from ATP  Proton ion gradient ATPase Na+/K+ ATPase Pump (an antiporter)  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Action potential propagation Trigger zone 3 2 1 Action potentials in the 2 Action potentials are 3 Action potentials result in communicating neuron propagated down the communication of the stimulate graded potentials in axon to the axon terminal. neuron with its target. a receiving neuron that can summate at the trigger zone. Ca2+ 1.2 mM Ca2+ 1.2 mM Ca2+ 10-4 mM Neurons, cardiac, skeletal and smooth muscles The Erythrocyte Plasma Membrane Provides Examples of Transport Mechanisms  Simple Diffusion Facilitated Diffusion Facilitated Diffusion Active Transport In the capillaries of body tissues Carbonic Acid H2CO3 Chloride-bicarbonate anion exchange protein (antiporter carrier protein) In the capillaries of lungs Carbonic Acid H2CO3 Chloride-bicarbonate anion exchange protein (antiporter carrier protein)  Transport Proteins Conformational Hydrophilic change channel Carrier(Transporters or Channel(Pores) Proteins Permeases) Proteins  Bulk transport across the plasma membrane occurs by exocytosis and endocytosis