Isotonic solution the inside of the cell will have

 Isotonic solution - the inside of the cell will have the same concentration of ions
as the solution, so there is no net movement of water into or out of the cell (think
about injections).
 Hypotonic solution - the inside of the cell will have more solutes than the solution,
so water will rush in and cause it to swell and/or lyse.
 Hypertonic solution - there is more water present in the interior of the cell than in
the external solution so water leaves the cell and it becomes crenated

Final Note: Remember that these terms are relative - a solution with a 10%
solute concentration will be hypertonic to one with a 5% solute
concentration. However, the 10% solution is hypotonic to a solution with a
15% solute concentration.
A FEW HINTS ABOUT THE FOLLOWING EXPERIMENTS:
1. Set up experiment 1 first and get it going - it takes the longest.
2. Divide labor among the members of your lab group - at least 2 people should be
working on experiment 1.
3. Experiment 2 can be set up and done last - it only takes about 15-30 minutes.
4. Be sure to read through ALL the instructions before beginning any of the
experiments!
2

Lab 3 Nur 0002
Experiment 1: Concentration Gradients and Rates of Osmosis
In this experiment you will examine the effect of a concentration gradient on the speed
of water movement across a semipermeable membrane (dialysis tubing). You will
compare the rate of osmosis for 3 different known combinations of solutions and 1
unknown.
Bag Setup
BAG INSIDE BAG IN BEAKER
1 1% sucrose tap water
2 5% sucrose tap water
3 10% sucrose tap water
4 unknown C unknown D
MATERIALS:
Triple beam balance
Dialysis bags soaking in water
4 beakers, 1 funnel
Solutions: 1% sucrose, 5% sucrose, 10% sucrose, unknowns
Paper towels; watch
NOTE : Follow the procedure for each dialysis bag until completion before starting
another one - this experiment requires a sequence of timed measurements - don’t try to
prepare all the dialysis bags simultaneously!
1. Take one dialysis bag out of the beaker and tie off one end (instructor will
demonstrate how to tie off the bags to prevent leaks). Fill the bag with 10-15 mls
(actual amount is not that important) of 1% sucrose using the funnel. Squeeze any
air out of the bag, being careful NOT to use your fingertips (the oil on the skin of your
fingertips can damage the dialysis membrane). Tie off the opposite end of the bag.
2. Dry the bag thoroughly on paper towels, especially the knotted ends. Weigh the bag
on the balance (1 decimal place is sufficient).
3. Put the bag in a labeled beaker and fill with enough tap water to just cover the bag -
NOTE THE TIME.
4. Fill the second dialysis bag with10-15ml 5% sucrose, tie it off, dry it, weigh it, put it
in a separate, labeled beaker with enough tap water to cover the bag, and again
NOTE THE TIME.