Figure 1.Cut dialysis tubing hydrating in water in Beaker 25.After 10 minutes, remove one piece of tubing from the beaker. Use your thumb and pointer finger to gently rub the tubing between your fingers; this will open the tubing. IMPORTANT:WHILE YOU ARE WORKING WITH THE DIALYSIS TUBING YOU MUST KEEP IT WET. DIP IT BACK INTO THE BEAKER WITH WATER FREQUENTLY. IF YOU LET IT DRY OUT, YOU RISK TEARING THE TUBING. DO NOT SET IT DOWN OUTSIDE OF THE WATER FOR MORE THAN A 10-20 SECONDS.
BI205: Introductory Biology IIWeek 4 LabPage 3 of 96.Close one end of the tubing by folding over 2.0 cm of one end (this will become the bottom). Fold it again and secure with a yellow rubber band. Tie a knot in the remaining dialysis tubing just above or just below the rubber band. Be careful not to pull the knot tight until you have pushed it as close to the rubber band as possible. You do not want the knot in the middle of the bag.) This will create a seal and ensures that solution will not leak out of the tube later in the experiment. 7.To test that no solution can leak out, add a few drops of water to the tubing and look for water leakage. If any water leaks, tighten the rubber band and/or the knot in the tubing. Make sure you pour the water out of the tubing before continuing to the next step. 8.Repeat Setup Steps 5-7 with the remaining dialysis tubes, using one each of the remaining rubber band colors. You will use the second rubber band of each color to secure the tops of the tubes later. If you cannot manage to get both a knot and the rubber band on the bag, thisis acceptable as long as you get a good single seal that prevents leaks.9.After you have secured one end of each piece of tubing, and before you move on to the nextstep, put the pieces of tubing back into the water in Beaker 2. Again, do your best to avoid allowing the hydrated dialysis tubing to dry out.Figure 2.One end of dialysis tubing secured by folding/rubber band method, and with a knot.10. Prepare three stock solutions from the 60g bottle of sucrose powder in your lab kit. Reconstitute the sucrose powder according to the instructions provided on the bottle’s label. This will create your 30% stock sucrose solution. If you used warm water, allow your stock solution to cool to room temperature before you begin your experiment.11. Use the graduated cylinder and your three waste beakers (of any size) to create three 5-ml sucrose solutions at concentrations of 30%, 15% and 3% sucrose, respectively. Refer to the table below for the amounts of stock sucrose and water to combine for each concentration. Set these solutions aside.
BI205: Introductory Biology IIWeek 4 LabPage 4 of 9Experimental sucrose solution(final concentration)Amount of 30% stocksucrose solution neededAmount ofwater needed30%5 mL0 mL15%2.5 mL2.5 mL3%0.5 mL4.5 mL12. Make an additional 200 mL of 15% sucrose solution in Beaker 1 by mixing the 30% stock solution with water. Use the following dilution equation to solve for the necessary amount of stock solution.