CAUTION Do not plug in or unplug ^ ir the hot plate with wet hands. Use care to avoid burns when working with the hot plate. Do not touch the hot plate. Use tongs to move heated objects. Turn off the hot plate when not in use. Fill a 500 mL beaker half full with water, and heat it on a hot plate. You will use the beaker as a hot-water bath. Leave space on the hot plate for a 125 mL Erlenmeyer flask, to be added later.

While waiting for the water to boil, clamp a ^^ 125 mL Erlenmeyer flask to a ring stand. Add 6 g of the amino acid mixture to the flask. When the water in the beaker begins to boil, move the ring stand carefully so that the flask of amino acids sits in the hot-water bath. When the amino acids have heated for 20 minutes, measure 10 mL of NaCl solution in a graduated cylinder, and pour the solution into a second Erlenmeyer flask. Place the second flask on the hot plate beside the hot-water bath.

6. When the NaCl solution begins to boil, use tongs to remove the flask containing the NaCl solution from the hot plate. Then, while holding the flask with tongs, slowly add the NaCl solution to the hot amino acids while stirring.

7. Let this NaCl-amino acid solution boil for 30 seconds.

8. Remove the solution from the water bath, and allow it to cool for 10 minutes.

9. ^f^ CAUTION Slides break easily. Use caution when handling them. Use a dropper to place a drop of the solution on a microscope slide, and cover the drop with a coverslip.

10. Place the slide on the microscope stage. Examine the slide under low power for tiny spherical structures. Then, examine the structures under high power. These tiny sphere-shaped objects are microspheres.

11. CAUTION If you get the sodium hydroxide (NaOH) solution on your skin or clothing, wash it off at the sink while calling to your teacher. If you get the sodium hydroxide solution in your eyes, immediately flush your eyes at the eyewash station while calling to your teacher. Place a drop of 1% NaOH solution at the edge of the coverslip to raise the pH as you observe the microspheres. What happens?

12. In your lab report, make a table similar to the one shown below. Based on your observations of micro-spheres and cells, complete your table. Consider the appearance of microspheres and cells, their method of reproduction, their interaction with their environment, and any other characteristics that you observe.

13. /irk Clean up your lab materials, and wash your hands before leaving the lab.

Analysis and Conclusions

1. Suggest how the microspheres in step 10 were formed.

2. What did you observe when the pH was raised in step 11?

3. What does this suggest about the relationship of pH to microsphere formation?

4. Compare and contrast microspheres with living cells.

5. What characteristics would microspheres have to exhibit in order to be considered living?

6. How might the conditions you created in the lab be similar to those that are thought to have existed when life first evolved on Earth?

7. Predict what would happen to microspheres if they were placed in hypotonic and hypertonic solutions.

Further Inquiry

1. What do you think would happen if you added too much or too little heat? What happens to proteins at high temperatures? How can you test for the right amount of heat to use?

2. Do you think your microsphere experiment would have worked if you had substituted other amino acids? How can you test your hypothesis?

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