Origins Of Life Lab 4i5rk

Name_Tyler Toth_____________________ Name Sydney Gilkey__________________ Name_Julia Schaffer__________________ Name_Kendra Sherry_________________ A.P. Biology Lab: Origin of Life Guided Activity Results: Data Table Run 1

Run 2

Run 3

Run 4

Run 5

0

3

6

9

12

Number of Drops of 0.1M HCl pH

4.5

4.0

3.75

3.5

3.0

Concentration of hydrogen ions

3.2 x 10-5 mol/L

1.0 x 10-4 mol/L

1.78 x 10-4 mol/L

3.2 x 10-4 mol/L

1.0 x 10-3 mol/L

Solution Observations

Cloudy, Cloudier, white/clear, precipitate no looks like precipitate pulp

More pulp that clumps up, still cloudy

Precipitate is looser, collects at top and bottom, smaller

Precipitate is smaller, looks like bubbles.

21

5

15

20

6

0.1 mm

0.8 mm

0.07 mm Lots of small, one large.

0.05 mm Lots of tiny, one big.

0.07 mm

Number of Coacervates on slide Size of an average Coacervate

Analysis Questions: 1. Calculate the total magnification you used to view the coacervates. The total magnification we used to the view the coacervates was 40x. This is because the viewing lense was a magnification of 10x and the observation lense was 4x. Multiplied together, that equals 40 and is the total magnification.

2. Calculate the field of view (in micrometers) you used to view the coacervates. We placed our ruler into the field of view of our microscope at a magnification of 4x. We measured it as a width of 2.5 millimeters which converts into 2,500 micrometers.

3. Use the field of view measurement to estimate the size of coacervates you observed at the pH at which they were most abundant. The size of an average prokaryotic cell is about 1-3 mm and the average eukaryotic cell is about 20 mm in diameter. How does the size of the coacervates compare with the size of prokaryotic and eukaryotic cells? The coacervates were most abundant at pH 4.5, with 21 coacervates in the field of view. The coacervates were estimated to have a size of 0.1 mm on average. Compared to the prokaryotic and eukaryotic cells, the coacervates are very small, one-tenth the size of the smallest prokaryotic cell and one-two hundredth of the average eukaryotic cell.

4. Construct a graph using the pH and the number of coacervates formed. Title the graph and supply the following information: a. The independent variable is: _the pH of the solution___________ b. The dependent variable is: _number of coacervates__________

Plot the independent variable on the x-axis and the dependent variable on the y-axis. You may either paste the graph into this document or attach the graph to the back of this document.

5. Calculate the concentration of hydrogen ions for each pH value that you measured and place these values in the table. Be sure to include units in your calculation.

Laboratory Questions: 1. At what pH were the coacervates most abundant? The coacervates were most abundant at pH 4.5, with an average of 21 coacervates in the field of view. Slide 4, with a pH of 3.5, was close behind in number of coacervates at an average of 20 in the field of view. However, the average size of the coacervate was much smaller in pH 3.5, with an average of 0.08 mm, while those in pH 4.5 averaged 0.1 mm.

2. Describe any shared characteristics you observed between coacervates and living organisms. Coacervates are not living organisms, but they do possess some characteristics of living organisms. They have a selectively permeable membrane that allows molecules from the surrounding solution to be absorbed, which allows them to change shape. Also, coacervates will react to changes in pH, like living organisms do. However, because the coacervates do not posses the ability to maintain homeostasis, there will be less of them formed in a solution with a pH that is not optimal for their formation, where living organisms could simply change the unwanted pH with their homeostatic mechanisms.

3. What type of organic molecule is gelatin? Gum Arabic? What is the function of these types of organic molecules in unicellular organism? Gelatin is made up of protein macromolecules, and gum arabic is formed from carbohydrate macromolecules. In unicellular organisms, these organic molecules could function to provide a membrane that would separate the interior environment from the exterior. The carbohydrates could also provide energy for the organism. The proteins provide for a variety of necessary functions in living organisms, such as catalyzation, movement, defense, structure, hormones, and transport.

4. Why are cells considered a necessary precursor to life? Cells are a necessary precursor for life because they are the most basic unit where life can exist. Metabolic processes, reproduction, growth, energy processing are necessary functions for life that take place in cells, and these would have to have been present for more complex life to form from them.

5. Based on the results of this experiment, why would pH have been important in the origin of life? This experiment proved that the coacervates are affected by pH changes in the environment around them. The results showed that the coacervates were the biggest and most abundant in pH 4.5, and as the surrounding medium became more acidic, the coacervates became less abundant and smaller. Before the formation of life, a more acidic environment could have hindered the growth of coacervates, which were important steps in the origin of life.