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Today’s Class

Today’s Class. Review of Chapter 8.1 Membrane Properties (small quiz). Lab: Transport across a semi-permeable membrane Passive transport: OSMOSIS Lab Conclusion: Observation and results . 8.2 Transfer Across Cell Membranes.

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Today’s Class

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  1. Today’s Class • Review of Chapter 8.1 Membrane Properties (small quiz). • Lab: Transport across a semi-permeable membrane • Passive transport: OSMOSIS • Lab Conclusion: Observation and results

  2. 8.2 Transfer Across Cell Membranes • Molecules crossing the cell membrane are distinquished by 3 things? • All matter is in a constant state of motion. The amount (rate) of motion is dependent on? • Motion of particles results in a net movement toward areas of lower concentration of those particles. The difference in concentration between two areas is called a?

  3. Diffusion Lab: 8.2 – part A • This lab will reinforce what we have learned about passive transport across semi-permeable membranes • Please work in bench groups of 4 • Please practice SAFE LAB PROCEDURES! • Each student must hand in a description and explanation of any movement you observed. The description may be in the form of a data table.

  4. Diffusion Lab: 8.2 – part A Purpose: To investigate diffusion (Passive Transport) across a semi-permeable membrane. Materials: Rubber gloves, safety goggles, lab apron, 500ml beaker, tap water (300ml), 1 - 10cm dialysis tube, 2 elastics, paper towels, starch solution, plastic spoon, iodine solution (Lugol’s).

  5. Procedure: • One person from each group will gather the materials. Carry the materials in a safe manner. • Pour 300ml of lukewarm tap water into the 500ml beaker. • Submerge the 10cm dialysis tube into the water for 1-2 minutes. Remove the tube and constrict one end of the tube using an elastic. • Add a few drops of the iodine solution to the beaker of water so the colour of the water is pale yellow. • Open the other end of the tube by rolling it between your fingers. Using the plastic spoon, gently scope the starch solution into the tube until it is ¾ full.

  6. Procedure: • Constrict this end of the tube using an another elastic • Wash the sealed tube off under gently running lukewarm water. Pat dry the tube with paper towels. • Weigh the tube and it’s contents. Record the initial mass in your group table. • Submerse the tube in the beaker. Add more water if needed.Let the product sit for 25 minutes.

  7. 1 2 3 4

  8. Data table

  9. Chapter 8 Dynamic Cells http://kentsimmons.uwinnipeg.ca/cm1504/Image127.gif

  10. Passive Transport • Movement of materials across membranes without the input of energy is called passive transport. • There are 3 types of passive transport • Diffusion • Osmosis • Facilitated diffusion

  11. 1. Diffusion http://www.williamsclass.com/SeventhScienceWork/ImagesCellBricks/Diffusion.gif

  12. http://gotoknow.org/file/somluckv/Cell_membrane02.jpg

  13. Diffusion Across Membranes • Molecules diffuse across cell membranes. • Very small molecules can move between the phospholipid molecules from one side of the membrane to the other. • Cells do not expend any energy during this process. • Eg: O2 is always being used by the cell the concentration of O2 is always lower inside the cell compared to outside the cell.

  14. 2. Osmosis – Diffusion of Water • Most of the molecules that fill and surround cells are water (H2O). • The diffusion of water across a membrane is called osmosis.

  15. Osmosis – Diffusion of Water http://i77.photobucket.com/albums/j48/annahybrid/normal_osmosisweb.jpg

  16. Osmosis – Diffusion of Water • Water molecules move from areas of high concentration of water to areas of low concentration of water across a semi-permeable membrane.

  17. Osmosis http://www.biologycorner.com/resources/osmosis.jpg

  18. OsmosisPassive Diffusion of Water • If one solution has a high concentration of H2O and a low concentration of solutes relative to another solution it is called HYPOTONIC.

  19. Hypotonic http://www.williamsclass.com/SeventhScienceWork/ImagesCellBricks/hypertonic.jpg

  20. OsmosisPassive Diffusion of Water • If one solution has a low concentration of H2O and a high concentration of solutes relative to anothersolution it is called HYPERTONIC.

  21. Hypertonic http://www.williamsclass.com/SeventhScienceWork/ImagesCellBricks/hypotonic.jpg

  22. OsmosisPassive Diffusion of Water • If the concentration of water is equal on both sides of a membrane the solutions are called ISOTONIC.

  23. Isotonic http://www.williamsclass.com/SeventhScienceWork/ImagesCellBricks/isotonic.jpg

  24. Osmosis in Living Cells • Maintaining water balance across the cell membrane is essential to survival. • If the concentration of water outside the cell is greater than inside the cell water will flow into the cell (cells in distilled water).

  25. Water Movement A C D B http://www.kscience.co.uk/resources/ks5/as/cells/osmosis/Plasmolysis_and_recovery.jpg

  26. Osmosis in Living Cells • In plant cells, the cell’s contents swell (turgid) but the cell walls keep the cell from exploding. http://leavingbio.net/OSMOSIS%20AND%20DIFFUSION_files/image021.gif

  27. Osmosis in Living Cells • In animals cells, (with no cell wall) the cell will explode or rupture. http://www.wadsworth.org/chemheme/heme/cytoheme/hemepix/slide092.jpg

  28. Osmosis in Living Cells • If the concentration of water outside the cell is less than inside the cell, water will flow out of the cell (cells in salt water)

  29. Osmosis in Living Cells • In plant cells, the cell contents will lose water, shrivel and pull away from the cell wall (plasmolysis). • In animals cells (no cell wall) the cell contents will lose water and shrivel (crenated)

  30. Crenated Red Blood Cells http://labmed.hallym.ac.kr/hematol/Hematol-Cell-Lists/crenatedrbcs.jpg

  31. Membranes at Work • Water Purification • Reverse osmosis • Water is filtered, by pressure, through a membrane with pores that only allow water through. • All substances larger than water cannot pass through • These systems are used in houses where well water is too salty or larger systems can provide clean water during disasters or war.

  32. http://enr.construction.com/images2/2005/08/050815-20.jpg

  33. Membranes at Work • Kidney Dialysis • Blood is pumped through a synthetic semi-permeable tubing called dialysis tubing. • The dialysis tubing is immersed in a saline solution similar to blood. • Wastes in the blood move from the tubing into the solution by diffusion. • Because the salts and water are in equilibrium with the blood, there is no loss of salts and water from the blood.

  34. http://biomed.brown.edu/Courses/BI108/BI108_2008_Groups/group04/images/ppf/girl.pnghttp://biomed.brown.edu/Courses/BI108/BI108_2008_Groups/group04/images/ppf/girl.png

  35. Membranes at Work • Controlled delivery of medication. • Semi-permeable membranes deliver medications in a safe, controlled manner. • Transdermal patches on the skin use a semi-permeable membranes to deliver the medication at a constant rate. • This delivery method is used to deliver drugs that counter motion sickness, and nicotine to aid in stopping smoking. • Artificial vesicles called Liposomes can be used to transport medicines to specific sites in our bodies.

  36. Test Questions: TRUE or FALSE? • The amount (rate) of motion is dependent on the nature of particles, its state (gas, solid, liquid), and temperature. • Movement of materials across membranes with the input of energy is called passive transport. • In a crenated cell the turgor may cause the cell to swell and rupture. • If one solution has a low concentration of H2O and a high concentration of solutes relative to anothersolution it is called HYPERTONIC.

  37. Water molecules move from areas of _______ concentration of water to areas of _______ concentration of water across a semi-permeable membrane to maintain a (an) ______ condition. • High; Low; Hypertonic • Low; High; Hypotonic • High; Low; Isotonic • Low; High; Isotonic

  38. Diffusion Lab: 8.2 – part B • Observe the colour of the water in the beaker and the colour of the dialysis tube. Record observations on the data sheet. • One student weighs the tube and another records it on the data sheet. Students to take note of any change in mass to help answer the lab questions. • As a group they are to complete 3 questions on the back of the data sheet and submit at the end of the class.

  39. Data table

  40. Diffusion Lab: Questions As a group, answer all questions on the back of your group’s Data Sheet. Submit at the end of the class • Is iodine moving through the membrane osmosis or diffusion?  • Did the water move into the dialysis tube through the membrane? How can you explain this? • Did the starch move out of the dialysis tube through the membrane? How can you explain this?

  41. Next Class • Review of Chap. 8.2 Transport Across Cell Membrane • Introduction of the next lesson: Facilitated Diffusion

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