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The Effect of pH on the Formation of Coacervates in Gelatin

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Linsey Roth

on 13 November 2013

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Transcript of The Effect of pH on the Formation of Coacervates in Gelatin

The Effect of pH on the Formation of Coacervates in Gelatin Solution
What we learned...

What we did....


What happened...

Hydrochloric Acid
Sodium Hydroxide
Microscope view with 2 drops of Sodium Hydroxide
In the first part of this lab, after the group added a certain number of drops of Hydrochloric acid (HCl) each time to the solution, the number of coacervates continued to increase as the number of drops increased. With 0 drops of HCl, there was 7 coacervates present under the microscope. With 1 drop, there was 11, with 2 drops, there was 15, with 3 drops there was 17, and with 4 drops of HCl there was 21 coacervates. Alongside the increasing number of coacervates, the pH level became lower, or more acidic, as more drops of HCl were added, which is what was expected. Also, it appeared that as more HCl was added to the solution the cloudiness of the solution intensified and it became less and less clear.
In the second part, the group tested the effects of the amount of drops of Sodium Hydroxide, a base, on the number of coacervates. It seemed that there was not a constant increase or decrease in coacervates as more drops of Sodium Hydroxide was added. With 0 drops of Sodium Hydroxide, there was 4 coacervates present under the microscope. With 1 drop, there was 5, with 2 drops, there was 2, with 3 drops, there was 9, and with 4 drops of Sodium Hydroxide there was 2 coacervates. However, as expected, the pH level became higher, or more basic, as the number of drops of Sodium Hydroxide increased. Also, the solution became less cloudy and more clear as more drops were added.
Sodium Hydroxide
The purpose of this lab was to to create coacervates by combining a carbohydrate solution with a protein solution. In this lab activity, a solution of gum arabic was added to a solution of gelatin to form coacervates. Gum arabic is made up of carbohydrate macromolecules while gelatin is made up of protein macromolecules. This lab showed how the Earth was formed from many different molecules (coacervates). First, 4 mL of gum arabic solution was added to the gelatin solution. Then, in two separate testings, we added different amounts of drops of Hydrochloric Acid and also Sodium Hydroxide to the solution to test the change in the number of coacervates and their diameters. These two things were changed as more drops of either Hydrochloric Acid or Sodium Hydroxide was added.
The importance of coacervates is that they have took part in playing a major role in cell evolution according to Oparin- Haldane hypothesis.
Campbell, Neil A. , and Jane B. Reece. AP Bio. 8th ed.
Through this experiment we generated coacervates in an aquatic solution which had many qualities similar to living organisms. We learned that these aggregates are made up of organic macromolecules with selectively permeable membranes that you may find in living things. We also learned the importance of pH in the origin of life. As pH decreased in the lab, the number of coacervates increased. Relating this data to evolution in the origin of life, we have learned that when a population is very small, genetic drift may occur and according to the Hardy Weinburg Theory, the population will evolve over time. The pH scale can control how large the population is because more of these molecules can be formed with a lower pH, and less with a higher more basic pH. A second theme of biology that was evident in this lab is the levels of organization. The coacervates that were formed contained amino acids that are found in living organisms. As time went on, more chemical reactions occurred which increased the complexity. This is comparable to a cell and the origin of life because over time cells combined to form organisms, which eventually formed populations and more complex levels of organization.
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