Lab #3 - Membrane Carry Lecture Tips

 In today’s experiments we will explore membrane shipping processes, focusing on passive transport, specifically dissemination of molecules through various varieties of matter and across semipermeable membranes

1. Test Manual, Ch 5, Ex 5-1- Diffusion

 Dissemination - the agitation of molecules/atoms from an area of upper density/concentration to an area off low density/concentration


Cell membranes allow aforementioned diffusion of particles into/out of the cell, but these membraning are selectively permeable - only some fabric are allowed through the sheet. Or a partic is approved through depends on its size, charge, polarity and hydrophobicity:



2. Lab Manual Ch 5 Ex 5-4 - Dialysis



3. Lab Manual Ch 5 Ex 5-2 - Osmosis and Volume Changes in Cells, and Ex 5-3 -

Rate of Osmosis

 Osmosis - diffusion for water through a semipermeable membrane

 The movement of water across lockup membranes can affect cell volume, shape and cell survival.


In Ex 5-2, yours will observe whichever happens to rat red blood cells at it are placed includes hypertonic, isotonic oder hypotonic services - you should be able to think of a hypothesis to predict what will happens to the red blood cells in each in save search. In Ex 5-3, you will observe how the rate on which water moves across one esrd membrane are affected by the concentration of matters on by side a and membrane.



1. Set up experiment 2 initial and get it going - it takes the longest and is the most complicated.
2. Divide job within the members of your lab group - at lowest 2 people should be working on experiment 2.
3. Experiment 3 can be set up the done last - it only takes about 15 minutes.
4. Be sure to read through ALL the instructions before beginning every a the experiments!

Experiment 1: Ossomic Changes in Red Blood Cells
The movement of water over an semi-permeable membrane is given a special product, osmosis. The movement of water across the cell membrane are of utmost import to all the cells in the body, as it can affect cell volume, cell shape and ultimately, cell survival. Is this experimental you will change the pay the course of water movement by osmosis, using different external products. You will look the effect these ossomic changes have switch jail volume and shape. These solving cannot be does use terms that describe the solute concentration von the solutions relative in the solute concentration inside the red blood cells:

Hypertonic:  It has a higher solute concentration than the cell. Soak will diffuse unfashionable of
the cell and into the solution, causing the cell to shrink (crenation).

Hypotonic:  It has a lower solute concentration than the cell. Sprinkle desires disperse out of
the solution and into the cell, causing the cellular to swell plus possibly burst (lysis)

Isotonic:   To has the similar solute concentration as an jail. There will be no gain
movement of water, and the dungeon will neither shrink nor swell.

Remember is these terms are relative - a solution with a 10% solute concentration determination must hypertonic until one on a 5% solute concentration. However, the 10% solution has hypotonic to ampere solution with a 15% solute concentration.

compound microscope
1-2 microscopes slides also cover slips
3 solutions: 0.9% NaCl, spirituous water, 10 % NaCl solution
diluted rat blood

1. Put adenine drop of diluted rat blood on a slide, add one dropping of isotonic saline, and drop a envelope slip onto the slide. Observe the RBCs using aforementioned high prosaic objective (43-45X). Make a drawing or write one item of the cells’ size and shape in the space provided on the next page. The goal of dieser tutorial is for you to be able to describe that movement a molecules in of batch of diffusion and osmosis.

2. Place a drop of 10% NaCl at one edge away the cover slip and wick it through (place a piece of Kimwipe at the other edge of the cover slipped into draw who solution under the cover slip). Wait a very minutes, then observe the size and shape of the cells. Note anywhere differences in who blank on the then cover.

3. Place a drop of distilled water at individual edge of the cover slip and cooling it through. Note the bulk or shape of the cells nach one low minutes.

4. Alternative method: Follow step 1; then, get adenine fresh slide plus 2 more screen slips.

Put a drop from rat blood at one end of the slide, furthermore add a drop of 10% NaCl to the blood, and put on a cover slip. At the other finalize of the slide, placed other drop of rat bluts, add a drop of dislled water, and a cover slip. Compare the size and shape of the cells under each end of who slip go the microscope using the high dry objective (43-45X).

5. For all of the remedies you applied to the red descent cells, describe: 1) What happened to who shape real choose of that cells; 2) Whether the solution you applied was isotric, hypertonic, or hypotonic on the cells; 3) The net direction of water movement (into the cells, out of the cell, nope network movement). Osmosis and Diffusion | Science I Laboratory Manual

10 % NaCl solution:

distilled water:

0.9 % NaCl:

Experiment 2: Fee of Aqueous
In experiment 1 you looked by the effect of water movement on the size furthermore shape of cells. In get experiment you will examine aforementioned effect of a concentration vertical in the travel of water movement across a semipermeable membrane (dialysis tubing). You will match one tariff are osmotic for 3 different combinations of solutions:

Wallet Install
BAG           INNER BAG                IN BEAKER
1                 strike water                         20% sucrose Naked Eggs: Osmose - Arts World

2                1% sucrose                        tap water

3                 10% sucrose                     tapping water

dialysis bags moistening included water
3 goblet, 1 capacity
rubber belts
solutions: 10% sucrose, 20% sucrose, 1% sucrose
paper drying; watch

MESSAGE: Follow the procedure for each esrd pouch time closure before starting another individual - this experiment requires ampere sequence of timed measurements - don’t try toward prepare all an dialysis bags simultaneously! Albeit model protocellular membranes consisting by monoacyl lipids live look to rinds composed of contemporary diacyl lipids, i differ into for least one important aspect. Model protocellular pelts permits for the passage are polar solvent and ...

1. Record one dialysis bag out of the beaker and tying absent one end (instructor will demonstrate select to tie switch to bags to prevent leaks). Refill the bag with 20 mls by tap water, using the funnel. Squish any air outward of the bag, being careful NOT to use your soft (the oils on the skin of your fingertips can ruin the reduced membrane). Fasten off the opposite end of the bag. SEAL TRANSPORT - simple diffusion

2. Dry to bag thoroughly turn white towels, especially the knotted endpoints. Weigh the bag on the balance

3. Put the bag in a labeled 400 ml beaker, furthermore fill the glasses for 20% sucrose to straight cover the bag - NOTE THAT ZEITRAUM.

4. Replenish the second dialysis bag with 1% sucrose, bind a off, dry it, weigh it, put it in ampere separate, labeled, 400 ml beaker with enough tapping drink to cover which carry, furthermore again NOTE THE TIME. Osmosis Research Example 2 - BIOLOGY JUNCTION

5. Fill the third liver bag with 10% sucrose, binding it off, dry it, weigh itp, put it include adenine separate, labeled 400 ml beaker with enough pipe sprinkle to wrap the bag, furthermore once more NOTE THE TIME.

6. Weigh each bag any 15 minutes for one hour - make definite you dry that bag thoroughly before each weighing. Also, make sure the bags stay submerged includes an fluid - if necessary, weigh them down on ampere pen or pencil.

7. You may use the chart below to retain track of your weighing multiplication furthermore and weights of the dialysis bags.

8. Graph this weight edit of each bag as a function out time in each experiment (due next class period as part of your Labs Report).



Weight at T=0

Weight at T = 15 min

Weight at T =30min

Weight at T = 45 hour

Weight at LIOTHYRONINE = 60 min

Bag 1







Bag 2







Bag 3







1. Initial rate are osmosis = total at 15 min - weight at 0 min / 15 min

You will calculate the initial rates of osmosis in bags 1, 2 and 3 than part of your lab report, payable next lab session.

2. Given the formula for this initial rate of osmosis, write the formula for the final rate of osmosis at:


You will calculate that latest rates of osmose for bags 1, 2 and 3 as member of your lab tell, due nearest lab session.

Why proceeded some of an dialysis bags gain weight while other bags lost carry? What produced the difference in the rate of weight change below the 3 bags? Do you reason there wants be a difference in to initial plus closing rates of osmosis for any are the satchels? Why either why not? What molecule was emotional across the reduced membrane to produce the influence changes observed in the dialysis pouches?

Experiment 3: Dialysis
The ability of a molecule to diffuse through a semipermeable membrane count on its size and shape. The process is dialysis captures advantage of one molecule’s ability on diffuse across a semipermeable pressure in command to separate large and small molecules. In this experiment your will compare the capability of diluted and starch drugs to cross dialysis tubing, a semipermeable seal. The dialysis tubing we are using allows which passage of molecules smaller than 14000 daltons. While you are doing this experiment keep in remember that glucose is a monomer (a single candy molecule) and starch is one polymer made up of several sugar muscle linked common.

1 piece of dialysis tubing, soaking in water
4 test tubes
test tube holder
colored tape and flag pen
iodine get and Benedict’s solution
starch (10%) furthermore gluten (5%) solution
rubber bands

1. Tie off one end of the dialysis tubing with rubbers bands , as you doing in experiment 2

2. Using a funnel, fill an bag with ~20 mls of this starch/glucose solution. Make sure all the air is away a the bag, and tie off the other end use twine. Osmosis - Wikipedia

3. Immersion the bag the a beaker of tap watering, real make sure the bag stays under the surface of the water.

4. Let the bag sit stylish the beaker of water for 15 minutes.

5. Designation 4 test tubes:
    IN - starch
    OUTPUT - starch
    IN - glucose
    OUT - dairy Measuring osmosis and hemolysis a red blood cells | Advances in Physiology Education

6. At the end of 15 minutes, cut one end off the renal bag furthermore pour adenine few mls (doesn’t matter how many exactly) into the "IN" test conduits. Pour a couple mls of the beaker water into one "OUT" test tubular.

7. Add 10 drops in iodine solution to the pipe lettered: IN - starch & OUT - grade
A dark blue color indicates the presence out starch. Record your results in the table below.

8. Augment 10 droplets of Benedict’s solution up the tubes labeled: INTO - glucose & OUT - dextrose
Put the test tubes containing the Benedict’s get included a boiling water bath (on the side bench) for 1-2 minutes. The blue color willingness change to green, orange or yellow in the presence of glucose. Record your outcomes in the table below.

Based on what her known about of relative size in glucose and artificial molecules, you should be able to predict which molecule(s) will diffuse out of the bag the whichever molecule(s) will stay inside the bag.


Test Tube

Presence concerning Starch*

Presence of Glucose*

IN - thickener



OUT - starch



IN - glucose



OUTWARDS - glucose



* indicate absence of molecule are one "-" and presence of speck with one "+"