Lab Report

Discovery of Coacervates

Coacervates Lab

Formation of Coacervates through carbohydrates and proteins

AP Biology mod 19

Abstract. The theory of creating coacervates (what appear to be living cells) was accomplished through mixing gum arabic, hydrochloric acid, and gelatin. We were able to observe the coacervates created through a microscope. We found them to be quite a bit smaller than what was originally expected, and acted as if they were, in fact, living. Using the procedure, we were able to create coacervates.

Introduction

In this lab, we observed the creation of coacervates through a microscope in order to better understand their existence, and how they are created. The coacervates were not present until the hydrochloric acid was added to the mixture. Changing the pH of the gelatin/gum arabic (protein/carbohydrate) mixture aided in the formation of these cell-like structures. At a higher pH balance, the mixture created these coacervates.

The idea behind the lab was to prove that life-like structures require very minimal ingredients/procedures. Naturally occurring carbohydrates and proteins being introduced into coacervates could easily take place outside of the lab. We were able to prove this with our findings.

We hypothesized that if we followed all of the procedures for creating coacervates, then we would be able to observe them through the microscope.

Methods

1. Put on safety goggles.

2. Half fill a tiny test tube with the pre-made mix of a 5:3 ratio of gelatin and gum arabic.  Note that the mix is clear; there are no coacervates in the mix.

3. Using short thin straw, transfer a tiny drop to pH paper, record this initial pH in a table.

4. Carefully add one drop acid (0.1M HCl) from a dropping bottle. Cover the mouth of the test tube with parafilm and turn it upside down so the acid mixes gently with the "Mix".  If it doesn't get real cloudy, repeat. Should require no more than one or two drops of acid. Cloudiness indicates presence of coacervates.

5. When cloudy, use short plastic straw to transfer one drop to pH paper, and one drop to a clean microscope slide. Read and record pH in a table.

6. Place a coverslip on the drop, and observe under the microscope. Look for coacervates (see example above).  Note:  a small diaphragm opening works best for this.

7. When you find good coacervates, sketch a few in your lab book.

8. After sketching coacervates, add another drop of acid to mix in test tube, turn it upside down to mix it in, and repeat until the extreme cloudiness disappears, and the mix becomes relatively clear again (should take only 2-3 additional drops of acid to do this). When this happens, check and record the pH. Observe if you have the time (coacervates should be gone).

Results

Coacervates Test Tube Sample Observations:

Procedure	pH level, Test 1	pH level, Test 2	Observation Test 1	Observation Test 2
0 drops HCl added	12	12	mostly clear, slight clouding	mostly clear, slight clouding
1 drop HCl added	did not test	did not test	moderate clouding	moderate clouding
2 drops HCl added	13	13	mostly cloudy	mostly cloudy

Sketches of Observed Coacervates:

Discussion

Although we were able to observe coacervates in this lab, it took an extensive amount of searching. Some of the other groups were able to operate on just one drop of Hydrochloric acid, while ours received two and still presented difficulty.

A main contributor could have been the air bubbles that formed underneath the glass, causing gap areas between the slide and the slide coverslip. This could have been a difficult environment for coacervates to form, and thus explaining why we were unable to find them without extensive searching.

Coacervates are not living creatures, they can move but that is where the similarities end. Unlike living cells, the coacervates have no way of reproducing or growing. It is not able to obtain nutrients from its outside environment and cannot control the environment.

It is suggested that coacervates played a significant role in the evolution of cells but once cells became established, their role became less significant.

In order to consider living, the coacervates would need to have the ability to grow or reproduce. Also the coacervates would have to be able to control or gather nutrients from the environment around them.

Conclusion

The purpose of this lab was to observe and understand the existence of coacervates in a high pH level environment. In the end, our hypothesis was correct as we were able to observe the coacervates existence and movements through a microscope. We now understand that the mixture of gum arabic, gelatin, and hydrochloric acid can create coacervates, which appear to be life-like, cell-like structures. However, we know that these phenomena are not actually living because they do not demonstrate all five definitions of a living organism.

Literature Cited

Flammer, L. (1999). Creating Coacervates. Indiana University, Science. Indiana University.