Lecture 7: Nutrients - Membrane Transport PDF

Week 1 Tue 10th Sept Lecture Module Introduction Week 2 Mon 16th Sept Lecture 1 Use of mammalian cells Tue 17th Sept Lecture 2 Cell Culture Laboratory Lab layout, Equipment and Materials Week 3 Mon 23rd Sept Lecture 3 Contamination control...

Week 1 Tue 10th Sept Lecture Module Introduction Week 2 Mon 16th Sept Lecture 1 Use of mammalian cells Tue 17th Sept Lecture 2 Cell Culture Laboratory Lab layout, Equipment and Materials Week 3 Mon 23rd Sept Lecture 3 Contamination control Tue 24th Sept Lecture 4 Contamination control Week 4 Mon 30th Sept Lecture 5 Contamination control Tue 01st Oct Lecture 2, 3, 4 and 5 recap and sample assessment questions Week 5 Mon 07th Oct Lecture 6 Nutrient uptake Tue 08th Oct Lecture 7 Nutrient uptake and sample assessment questions Week 6 Mon 14th Oct Lecture 8 Biology of Culture Cells Tue 15th Oct Lecture 9 Cell culture media Week 7 Mon 21st Oct Lecture 10 Cell culture media Tue 22nd Oct Lab 3 data analysis Reading Week Week 8 Mon 04th Nov Lecture 11 Cell Culture Media Tue 05th Nov Lecture 8, 9, 10 and 11 recap and sample assessment questions Week 9 Mon 11th Nov Lecture 12 Growing mammalian cells Tue 12th Nov Lecture 13 Monitoring growth Week 10 Mon 18th Nov Lecture 14 Cryopreservation of cells Tue 19th Nov Lecture 12, 13 and 14 recap and sample assessment questions Week 11 Mon 25th Nov Lecture 15 Innate immune response Tue 26th Nov Lecture 16 Adaptive immune response & Bioassays Lecture 15 and 16 recap and sample assessment questions Week 12 Mon 02nd Dec Revision Tue 03rd Dec  Nutrients - Membrane Transport Lecture Overview Introduction: Why discuss this topic Main discussion: Nutrient uptake mechanisms Conclusion: Take home message BIOT6012 Mammalian Biotechnology Lecture 7 Slide 2  Nutrients - Membrane Transport Introduction Before you can manipulate cells to produce large amounts of desired products or services you need to understand their nutritional requirements BIOT6012 Mammalian Biotechnology Lecture 7 Slide 3  Nutrients - Membrane Transport Passive Transport (cell doesn’t use energy) 1. Diffusion (lecture 6) 2. Osmosis (lecture 6) 3. Facilitated Diffusion Active Transport (cell does use energy) 1. Protein Pumps 2. Endocytosis 3. Exocytosis BIOT6012 Mammalian Biotechnology Lecture 7 Slide 4  Nutrients - Membrane Transport Passive Transport Facilitated Diffusion Transport of molecules and ions across the membrane down their concentration gradients i.e. area of high concentration to area of low concentration. Facilitated by transport proteins. No energy input required. BIOT6012 Mammalian Biotechnology Lecture 7 Slide 5  Nutrients - Membrane Transport Passive Transport Facilitated Diffusion 1. Carrier protein Bind solute, conformation al change, release Selective binding Solute Carrier protein A carrier protein alternates between two conformations, moving a solute across the membrane as the shape of the protein changes. The protein can transport the solute in either direction, with the net movement being down the concentration gradient of the solute. BIOT6012 Mammalian Biotechnology Lecture 7 Slide 6  Nutrients - Membrane Transport Passive Transport Facilitated Diffusion 2. Channel protein EXTRACELLULAR FLUID Aqueous channel, hydrophilic pore, very rapid selective – size/charge Channel protein Solute CYTOPLASM A channel protein (purple) has a channel through which water molecules, or a specific solute can pass. BIOT6012 Mammalian Biotechnology Lecture 7 Slide 7  Nutrients - Membrane Transport Active Transport Movement of a substance against its concentration gradient i.e from an area of low concentration to an area of high concentration. Requires metabolic energy and transport proteins. BIOT6012 Mammalian Biotechnology Lecture 7 Slide 8  Nutrients - Membrane Transport Active Transport - Sodium-Potassium Pump 1. A transport protein in the membrane has specific receptors for sodium ions and binds three ions and a phosphate group from ATP. 2. The splitting of ATP provides energy to change the shape of the channel. The sodium ions are driven through the channel (note change in shape of protein channel). 3. The sodium ions are released to the outside of the membrane and the new shape of the channel allows two potassium ions to bind. 4. Release of the phosphate allows the channel to revert to its original form, releasing the potassium ions on the inside of the cell BIOT6012 Mammalian Biotechnology Lecture 7 Slide 9  Nutrients - Membrane Transport Items Passive Facilitated Active diffusion diffusion transport Carrier Proteins Transport speed Against Concentration Gradient Specific for Specificity Specificity No specificity molecules transported Metabolic energy needed BIOT6012 Mammalian Biotechnology Lecture 7 Slide 10  Nutrients - Membrane Transport Endocytosis and Exocytosis is the mechanism by which very large molecules (such as food and wastes) get into and out of the cell Food is moved into the cell by Endocytosis Wastes are moved out of the cell by Exocytosis BIOT6012 Mammalian Biotechnology Lecture 7 Slide 11  Nutrients - Membrane Transport Endocytosis Process in which a substance gains entry into a cell without passing through the cell membrane. - macromolecules, large particles, small molecules, and even small cells brought into the eukaryotic cell. Pinocytosis (small particles) 250px-Pinocytosis Three types: phagocytosis, pinocytosis, and receptor-mediated endocytosis. In all three: Plasma membrane folds inward around materials forming a small pocket. Phagocytosis (large particles) The pocket deepens, forming a vesicle. This vesicle separates from the plasma membrane and migrates with its contents to the cell’s interior. This is how white blood cells eat bacteria. BIOT6012 Mammalian Biotechnology Lecture 7 Slide 12  Nutrients - Membrane Transport Receptor-mediated Endocytosis A specific receptor on the cell surface binds tightly to the extracellular macromolecule that it recognizes. The plasma-membrane region containing the receptor-ligand complex then undergoes endocytosis, becoming a transport vesicle. Receptor is recycled back to the plasma membrane. Examples of macromolecular ligands that vertebrate cells internalize by receptor- mediated endocytosis are cholesterol-containing particles called low-density lipoprotein, transferrin and insulin. BIOT6012 Mammalian Biotechnology Lecture 7 Slide 13  Nutrients - Membrane Transport Exocytosis Forces material out of cell in bulk Membrane surrounding the material fuses with cell membrane Cell changes shape – requires energy e.g. Hormones or wastes released from cell BIOT6012 Mammalian Biotechnology Lecture 7 Slide 14  Nutrients - Membrane Transport Conclusion Nutrients enter the cell via passive or active transport mechanisms. Passive transport mechanisms do not require energy input and involve simple diffusion of solutes across the membrane. Passive transport can occur with or without involvement of a protein to facilitate diffusion. Active transporters always require energy input and involve dedicated transport proteins embedded in the cytoplasmic membrane e.g. Protein Pumps, Endocytosis, Exocytosis BIOT6012 Mammalian Biotechnology Lecture 7 Slide 15