Exercise 6.1 - Lipid Solubility of Membranes
- Fresh beets
- Solutions of the following alcohols:
- 22 M Methanol
- 8.5 M Ethanol
- 3.0 M n-Propanol
- 1.1 M n-Butanol
- 0.38 M Amyl alcohol (Optional)
- Razor blades
- Depression slides
- Beet cells contain a high concentration of the red pigment
anthocyanin. When exposed to a compound which dissolves the cell
membranes, the anthocyanin will leak out of the cells and cause a
red color to occur in the surrounding media.
Cut thin slices of a beet so that they can be placed on a
microscope depression slide and viewed with the lowest power
- While watching the edge of the sliced beet, add
approximately 1.0 ml of each of the above alcohols to the slide,
until the beet section is submerged. Be careful not to allow the
alcohol to flow off the slide.
Iso-amyl alcohol has a strong, obnoxious odor and the fumes
are somewhat irritating. Adequate ventilation is required.
- Immediately begin to time the dissolution of
the beet cell membranes. Mark the time when a red color is first
observed in the surrounding alcohol solution.
- Repeat the entire series for 1/2 and 1/4 dilutions of each
of the alcohols.
- For each dilution of each alcohol, calculate a penetration
coefficient by dividing the time of pigment appearance by the
molar concentration of the alcohol. In the space given on page
137, plot this penetration coefficient against the relative
miscibility of the alcohol (known as the partitition or
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Cell Biology Laboratory Manual
Dr. William H. Heidcamp, Biology Department, Gustavus Adolphus College,
St. Peter, MN 56082 -- firstname.lastname@example.org