LAB 8: DIFFUSION AND OSMOSIS SECTION T2AB
Safety Reminder • NO phones – A lot of you are losing points from your final grade! • NO drinks, NO food • Use gloves when handling chemicals or wash your hands after setting up the experiment • Chemicals this week and next, then dissections - may wish to bring a lab coat or large shirt
Agenda 1. Procedure 9.6 modified! You set up the experiment 2. Procedure 9.4 modified! 2ml in each bag only • Record weight every 15 min 3. Procedure 9.3 modified! 2 ml in each bag only, use distilled water, iodine: 40-50 drops = light brown color • Record observations every 20 min 4. Lecture 5. 4 remaining procedures (9.1, 9.2, 9.7, 9.8) 6. Check potato experiment after 2 hours and record weight
Procedure 9.6 (potato) 1. Each group : combine 100 ml of your designated NaCl (salt) solution and 100 ml of distilled water into 250 ml (or larger) beaker. Label the beaker with the NaCl % 2. Use borer to obtain 3 pieces of potato core . Blot and record weight of 3 pieces together to nearest 0.01 gram (Table 9.2). 3. Transfer potato pieces to beaker and record time. 4. Incubate for 2 hours, swirling beaker every 15 minutes. 5. Blot and weigh potato pieces after 2 hours. Record weight and time (Table 9.2). Group 1 2 3 4 5 NaCl % 15% 0% 0.9% 5% 10%
How to use serological pipettes • Use the smaller pipette with the smaller filler and large with large • Roll the wheel with your thumb to fill and empty • After using: • place filler back into box • place pipette into pipette washer on floor next to sink
Procedure 9.4 (sucrose dialysis) 1. When preparing dialysis bag, put label on string before wetting it. • Remove air bubbles, tie the string very well - must avoid contamination / leakage between bag and beaker! 2. Put 2 ml (NOT 10 ml) in each bag! 3. Wet the string before weighing to get accurate initial weight of bag 4. Submerge tied bags in beaker solution – all together at the same time
Procedure 9.6 (potato) 1. Each group : combine 100 ml of your designated NaCl solution and 100 ml of distilled water into 250 ml (or larger) beaker. Label the beaker with the NaCl % 2. Use borer to obtain 3 pieces of potato core . Blot and record weight of 3 pieces together to nearest 0.01 gram (Table 9.2).
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