Transcript Week6-Video
Diffusion, Osmosis & Passive Transport Student Self Study Movement across a semi-permeable membrane CAE 507 Video & Multimedia for Education by Karen Reback Nova Southeastern University June 10, 2007 Lesson Goals & Learning Objectives: To gain a better understanding of both active and passive transport and how they relate to plant and animal cells After viewing the presentation, and accessing the links; students will be able to compare and contrast the basic mechanisms of passive and active transport across the cell membrane with 100% accuracy After viewing the presentation, and accessing the links; students will be able to describe osmosis and diffusion concepts with 100% accuracy. These lessons are geared toward High School Biology students At the cellular level, many things are occurring every second, which we are generally not able to visualized. Using a large cell (egg), the student will be able to see how the semipermeable membrane “works”; allowing some materials to pass while others do not. The project will show osmosis, the movement of water across a semi-permeable membrane. Students, will need to read, and interpret the given information and data, drawing conclusions and taking those conclusions to further levels of analysis. Once the student has seen passive transport in action, the student will then need to create, test and complete an original experiment involving some form of passive transport. Itinerary Front Door - Evaluation Tag CHE (concrete, humanistic, easy) I choose this front door because it patterned after a daily diary, in this case an egg. The evaluation tag “C”oncrete is based on specific facts. “H”umanistic, encourages affective examination of the material. “E”asy this front door can be revised and translated easily. Begin your virtual tour of movement across a semi-permeable membrane – Click on the given containers to see what happens during that time Prior to the egg being placed into the vinegar 24 hours after the egg has been placed in the vinegar 48 hours after the egg has been placed in the vinegar 72 hours after the egg has been placed in the vinegar 24 hours after the egg was removed from the vinegar and placed in corn syrup Lesson Overview • Cellular Transport is movement of materials across a semipermeable membrane. • Cellular Transport can be broken into active and passive transport. • Passive Transport is the movement of materials across a semi-permeable. membrane, from an area of high concentration to an area of low concentration (down the concentration gradient). • Active Transport is the movement across a semi-permeable membrane from an area of low concentration to an area of high concentration. Active transport requires that energy is added. Instructions • Click on the forward arrow to advance to the next slide; the back arrow to return to the previous slide. Arrows will have specifically where you are headed if not just front or back. Answer each question carefully. • Time – You will have 60 minutes to complete the lesson. What do you know about Cellular Transport? Which condition might cause a cell to burst? – Click on the cell next to your Answer choice… A B C D Which way do you predict water will move and why? Click on the Corresponding Water Molecule for your answer. From left to right against its concentration gradient. From right to left against its concentration gradient. From left to right along its concentration gradient. From right to left along its concentration gradient. Active Transport Question How are the dissolved ions moving? Click on the ion next to your answer: 1. 2. 3. 4. Against their concentration gradient. With their concentration gradient. From high concentration to low concentration Both 1 & 3 Previous question More information Water moves to the left High Solute – Low Water High Water – Low Solute The movement of materials into and out of the cell is very import to how plants and animal cells function on a daily basis… Sugar molecules that cannot pass through the membrane Water molecules can move with the concentration gradient As you can see the water molecules are the only thing that passes across the semi-permeable membrane Hypertonic Solution Hypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. solute water Hypotonic Solution Hypotonic Solutions: contain a low concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode. solute water Isotonic Solution Isotonic Solutions: contain the same concentration of solute as an another solution (e.g. the cell's cytoplasm). When a cell is placed in an isotonic solution, the water diffuses into and out of the cell at the same rate. The fluid that surrounds the body cells is isotonic. solute water Animal Cells Animal cells are effected daily by the differing types of solutions. Isotonic is when everything is in balance between the cell, blood and body chemistry. You have experienced a hypertonic solution, when your cells are put into a into a solution that has more water inside the cell then outside the cell. Water will leave the cell and the cell shrinks and shrivels. A practical example of this is when you use saline nose spray. The saline (salt) content is higher outside the nose cells which means lower water. Water leaves the cells. This helps to remove excess water from a runny nose!! Your have experienced a hypotonic solution when you eat something with a lot of salt. Your fingers swell; the salt enters your cells; there is more salt inside the cell, which means less water, the Water moves into the cell, causing a swelling, our body has mechanisms to prevent the cells from bursting. Can you figure out more examples?? Plant Cells Plant cells will live but not thrive in isotonic solution, plants do better with an increase in turgor pressure which results from a full vacuole. Hypertonic solutions exist when plants are in very dry environments and there is more water inside the cells then in the atmosphere – water will leave the cells and go into the environment. The plant’s leaves may wilt. Plant plants prefer hypotonic solutions when the pressure in the central vacuole is high, the plant is able to retain it’s shape well. Often business place lettuce and spinach in distilled water to create the appearance of fresh plump vegetables . So what did you learn? Answer the following and submit to the teacher for a grade. • Compare and contrast the basic mechanisms of passive and active transport across the cell membrane. • Describe osmosis and diffusion. • To show complete mastery of the subject and a great way to earn bonus points, design a lab that will demonstrate osmosis, diffusion or both. References Active Transport Image from http://school.discovery.com/quizzes13/zagzoo/CellSFTrans.html , Retrieved May 20, 2007 Animal Cell & Plant Cell Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com), Retrieved May 20, 2007 Egg Image from http://www.exploratorium.edu/cooking/eggs/images/naked2.jpg Retrieved May 14, 2007 Tomei, L (2001). Teaching Digitally: A Guide for Integrating Technology into the Classroom. Norwood, MA: Christopher-Gordon Publishers. W.H. Freeman, (2007). Cellular Transport Images and Questions. www.whfreeman.com Retrieved May 20, 2007 W.H. Freeman, (2007). Animated Tutorial Active Transport from http://bcs.whfreeman.com/thelifewire/content/chp05/0502002.html, Retrieved May 27, 2007 W.H. Freeman, (2007). Animated Tutorial Passive Transport from http://bcs.whfreeman.com/thelifewire/content/chp05/0502001.html, Retrieved May 27, 2007 The End… If you have any question or problems – please contact me at [email protected]