FREE ESSAY ON STUDY OF THE ENVIROMENT ON THE CELL MEMBRANE

STUDY OF THE ENVIROMENT ON THE CELL MEMBRANE

Study Of The Enviroment On The Cell Membrane
Dave Lima
SBI OA1
Mr. Swanson
10/4/99
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
Materials & Method
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.
a) 10 mL of 0.1 mol/L HCl
b) 10 mL of 0.01 mol/L HCl
c) 10 mL of 0.001 mol/L HCl
d) 10 mL of distilled water
e) 10 mL of 0.001 mol/L NaOH
f) 10 mL of 0.01 mol/L NaOH
g) 10 mL of 0.1 mol/L of NaOH
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
Materials & Methods
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.
Observations:
Analyzing anthocynanin by adding concentrated acid and base to beet juice
Mixture Observations recorded
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.
Serial Dilution
Intervals 0.1 mol/L 0.01 0.001 Distilled` 0.001 0.01 0.1 
HCl mol/L mol/L Water mol/L mol/L mol/L
HCl HCl NaOH NaOH NaOH
15 -lots of -less pigment -a small -very little -a small -barely -a yellow
Minutes pigment lost lost than the amount pigment lost amount any pigment is
-solution is dark 0.1 solution of from the beet of pigment present in
purple in of HCl pigment root pigment lost the 
colour lost lost from the solution
from the from the beet root 
beet root beet root 
30 -slightly -slightly -slightly -slightly -slightly -slightly -slightly
Minutes more more more more more more more
Pigment pigment pigment pigment pigment pigment pigment
lost since lost since lost lost since lost lost lost
the the since the the since since since
observation observations obser- observations the the the
made at made at vations made at observ- observ- observ-
15 minutes 15 minutes made at 15 minutes ations ations ations
15 made at made at made at
minutes 15 15 15
minutes minutes minutes
45 -solution -solution -solution -a darker shade -solution -solution -the
Minutes is dark is pink in is a of pink than is a light is a light mixture is
purple in colour lighter the 0.001 pink pink very
colour throughout shade of solution of through- through- yellow
throughout pink HCl but not out the out the throughout
than that of the mixture, mixture, the actual
the 0.01 0.01 solution similar similar beet have
solution of HCl to that to that turned
of HCl of the of the brown in
0.001 0.001 colour
mol/L mol/L
HCl HCl
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 water Test tube with 10 mL of water and 2 mL of ethanol
-very little pigment lost
-light pink in colour
-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
Discussion
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.
Conclusion:
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.