Study Of The Enviroment On The Cell Membrane
Purpose: To study the effect of environmental changes in the permeability of living beet root cells.
Procedure A: The effect of pH on the cell membrane
1. Cut a beet root into slices approximately 2mm thick. Use a cork bore to cut out thirty-five (35) slices.
2. Place the discs in a 250 mL beaker and rinse thoroughly in cool running tap water. The red pigment collected comes from the damaged cells and can be used to analyze the chemical nature of the pigment.
3. The pigment in a beet, anthocynanin, should be analyzed before beginning. This can be done simply by first adding a few drops if concentrated acid to a sample if beet juice.
4. The resulting solution can be compared to a second sample made by adding a few drops if concentrates base to another sample of beet juice. Note the colours of each. Given stock solutions of 0.1 mol/L HCl and 0.1 mol/L NaOH, and graduated cylinders, prepare the following solutions in separate test tubes.
5. Place five (5) beet root discs in each of the 7 test tubes.
6. Leave them for 15 minutes and then record your observations. Agitate gently and continue to observe them at 15-minute intervals until no further changes occur.
Procedure B: The effects Of An Organic Solvent
1. Prepare beet root discs as for Procedure A. The number required will depend on the control you design.
2. Place five (5) of the discs in a test tube containing 10 mL of distilled water and 2 mL of ethanol.
3. Design a control for this investigation.
4. Agitate gently and periodically for 15 minutes and record your observations.
Analyzing anthocynanin by adding concentrated acid and base to beet juice
Few drops of concentrated acid added to a sample of beet juice-Concentrated acid caused the anthocynanin to turn to a slightly lighter shade of pink.
Few drops of concentrated vase added to a sample of beet juice-Concentrated base caused the anthocynanin to turn a transparent yellow.
Intervals 0.1 mol/L0.010.001 Distilled`0.0010.01 0.1
HClmol/Lmol/L Watermol/Lmol/L mol/L
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45-solution-solution-solution-a darker shade-solution-solution-the
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The Effects Of An Organic Solvent: Designing A Control
The control our group designed for this investigation was to have one test tube with 10 mL of distilled water 2 mL of ethanol. This way both test tubes would have a total of 12 mL and 5 beet roots each.
Test tube with 12 mL of waterTest tube with 10 mL of water and 2 mL of ethanol
-beets moved (twirled) when agitated -very little pigment lost
-only a light tint of pink could be seen
-beets did not move when agitated, they remained at the bottom of the test tube
-traces of oil were present in the test tube
1. What relationship exists between the concentration of acid or base solution and the pH?
In a solution, pH refers to the concentration of H+ ions. The pH is expressed as a positive number while the concentration of the H+ ions is taken in exponent form. Bases start at as low as 10-14 and acids are up to 1. Therefore taking the pH from the concentration is determined by taking the negative value of the exponent of hydrogen concentration H+
2. How is the membrane affected by the different pH values of the solutions? What changes have the tested solutions created in the structure of the membrane?
The pH value of Hydrochloric acid is 0, and the pH value of the Sodium hydroxide is 14. The acid caused the membrane to “tear” from the damage caused by. The anthocynanin then permeated through the membrane. Since the pH value of the distilled water is 7, which is neutral, caused no damage to the cell membrane. The closer the substance was to neutral the more osmosis pressure was create around the sell membrane. Once the cell was full with as much water as it could with hold, the osmosis pressure rises. The Sodium hydroxide’s pH intensity was so high that it caused the cell membrane to degrade, which made permeability increase.
3. At which pH does the maximum intensity of anthocynanin, occur? At which pH does the least occur?
The pH that the maximum intensity of anthocynanin occurred at was at the 0.1 mol/L of HCl, due to the high pH content and the low dilution of the substance. The pH that did the least amount of damage to the cell membrane was the 0.001 mol/L of NaOH, due to the low pH content and the dilution of the substance.
4. Would you expect similar results using carrot roots (which contain an orange pigment)? Explain your answer.
The pigment of the carrot cell is orange and would probably make it more difficult to decipher between the pH levels. While the beet root makes it easier. At each different level that the pH was diluted at, made the pink fluid turn lighter, until the use of NaOH then it slowly became more yellow. This would be more difficult with the carrot root. The membranes also differ quite a bit.
5. Under what circumstances would be of important to plants? Animals?
If the pH inside of a cell, in a plant or animal is unbalanced and is either two high or two low it could cause destruction of damage top the cell which could cause the cell to die. The reaction to the beet root is a good example.
6. Compare the test tube with the organic solvent to the control, account for any changes seen.
The two different test tubes differed in many ways. In the organic the beets stayed at the bottom while agitated, while the other test tube the beets spun around the tube when agitated.
7. Suggest how the ethanol has affected the cell membrane.
Because both the water and the ethanol both have hydrogen bonds this could cause the beets to remain at the bottom of the test tube. When a polar solute, enters into water the water molecules surround the solute and it becomes no longer to diffuse through the membrane.
8. Would all organic solvents be likely to affect the permeability of the water membrane the same way? Explain.
No, not all-organic substances would affect the permeability of the cell membrane, as the ethanol did. The non-polar molecules would not go also with the hydrophilic heads of the phospholipids. As well as alkanes, alkenes, and alkynes.
A cell membrane reacts differently to it’s surrounding, which causes either a life or death situation for the cell. A pH with a very high, or a very low concentration, will cause damage to the cell, where a medium pH level will do very minimum damage to the cell. When damage is done to the cell, osmosis and diffusion become easier for outside solutions. When a cell reaches equilibrium (with water) it creates osmosis pressure. Osmosis pressure is when the hydrostatic pressure from inside the cell is greater then the pressure from outside the cell. Organic solvents also affect the permeability of the cell. Ethanol is miscible with water and both posses hydrogen bonds.