3 Lab 3 RBCs_OSMOSIS AND TONICITY_WooOnline_Sp21.docx - Lab...

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Lab Exercise 3: | Woo Sp 2021 Lab Exercise 3 (Two Parts): Determining Osmotic Concentration, Tonicity, and the Relative Effects of Different Solutions on Living Cells Review the concept of osmosis in your textbook (Silverthorn 8 th ed. Pp124-130; 7 th ed. pp. 125-132) & Solutions (Silverthorn 8 th & 7 th ed. pp. 42-43 Or Figure 2.7), prior to coming to lab. Read the entire document. Complete all of the exercises. Fill in everything in RED. You may use the draw feature on Word or other to handwrite the information in the lab but you must type your answers to the lab assignment questions at the end of this document Activities: 1. Intro to Tonicity and Osmosis: Video 2. What happens to RBCs in different solutions: Video Lecture (by Dr.Thomford) 3. RBCs as osmometer experiment: Video (Drs. Woo and Pentek) 4. Complete PhysioEX Exercise 1 Activity 3 Simulating Osmotic Pressure Objectives: Part 1: 1. Understand and apply the following terminology: osmotic concentration, osmotic pressure, osmotic equilibrium; penetrating solute (PS), non-penetrating solute (NPS) 2. When comparing 2 solutions separated by a semi-permeable membrane, be able to indicate their tonicity: hypertonic, hypotonic, isotonic 3. Apply your knowledge of osmosis and tonicity in physiological situations 4. Calculate osmotic concentration if given molar concentrations and the characteristics of the solute molecules involved 5. When comparing 2 solutions, be able to indicate their relative osmotic concentration (hypo, iso or hyper-osmotic); 6. Design a simple experiment that would test a given hypothesis related to osmosis and diffusion. Employ the steps to the scientific method in the experimental protocol. Part 2: 7. Observe changes that occur in living cells and be able to predict how the cell volume will change when placed into solutions of varying osmotic concentrations with variable tonicity. 8. Be able to use proper terminology to describe tonicity and osmotic concentration when comparing two solutions. 9. Employ the scientific method to test the following hypothesis: A living cell placed into a solution that is isotonic and hyperosmotic will not exhibit a net change in volume as measured by size when observed over time. Key Terms: Osmosis, selective permeability, hypertonic, hypotonic, isotonic, ICF, ISF, equilibrium, osmotic pressure, molarity, osmolality, ionic bonds, covalent bonds, hyperosmotic, hypoosmotic, isosmotic, hemolysis, osmometer, PS, NPS, crenation. Background Part 1: In last week’s experiment (Lab Exercise 2, Part 3) you demonstrated the processes of dialysis and osmosis across a non-living, semi-permeable membrane. You could tell that osmosis occurred because your dialysis bag gained weight. Osmosis is the net diffusion of water across a membrane . For osmosis to occur, the 1
Lab Exercise 3: | Woo Sp 2021 membrane must be 1) permeable to water, but 2) impermeable to some or all of the solutes; therefore, the membrane is considered semi-permeable (in living cells the term selectively permeable is used). When you have a difference in the concentration of non-penetrating solutes

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