Cellular Respiration Lab

Cellular Respiration Lab Report

Roxy Moghadam

F- Block

Mr. Quick

02/19/14

The Effect of Temperature on Cell Respiration

Abstract:

In this lab we tested yeast mixed with salt, water and sugar to see the process of cell respiration in different temperatures. We had four test tubes consisting of the same amount of substance and four different temperatures that the tubes would be placed in. We found that as the temperature increased, so did the rate of cellular respiration. This occurred because of the yeasts higher optimal temperature and molecular motion. 

Question:

How is cellular respiration affected when yeast, mixed with water, salts and sugar in four test tubes are placed in four different temperatures?

Background:

We all need energy to function and we get this energy from the foods we eat. The most efficient way for cells to harvest energy stored in food is through cellular desperation, a catabolic pathway for the production of adenosine triphosphate (ATP). ATP, a high energy molecule, is expended by working cells. Cellular respiration occurs in both eukaryotic and prokaryotic cells. It has three main stages: glycolysis, the citric acid cycle, and electron transport. The formula used for cell respiration C6H12O6+6O2----> 6CO2+6H2O+36-38ATP.

Glycolisis literally means "splitting sugars." Glucose, a sixcarbon sugar, is split into two molecules of a three carbon sugar. In the process, two molecules of ATP, two molecules of pyruvic acid and two "high energy" electron carrying molecules of NADH are produced. Glycolysis can occur with or without oxygen. In the presence of oxygen, glycolysis is the first stage of cellular respiration. Without oxygen, glycolysis allows cells to make small amounts of ATP. This process is called fermentation.

The Citric Acid Cycle or Krebs Cycle begins after the two molecules of the three carbon sugar produced in glycolysis are converted to a slightly different compound (acetyl CoA). Through a series of intermediate steps, several compounds capable of storing "high energy" electrons are produced along with two ATP molecules. These compounds, (NAD) and (FAD), are reduced in the process. These reduced forms carry the "high energy" electrons to the next stage. The Citric Acid Cycle occurs only when oxygen is present but it doesn't use oxygen directly.

Electron Transport system requires oxygen directly. The electron transport "chain" is a series of electron carriers in the membrane of the mitochondria in eukaryotic cells. Through a series of reactions, the "high energy" electrons are passed to oxygen. ATP synthase synthesizes ATP while protons diffuse back into the matrix. In the process, a gradient is formed, and ultimately ATP is produced. Increase in energy is produced by the increase in molecular motion (Bio class, Mr. Quick, 2014)

Hypothesis:

If four tubes of yeast, sugar, water and salt are put into four different temperatures, cellular respiration will increase and create greater molecular motion as temperature increases.

Materials:

Salt

Sugar

Room Temp. Water

Yeast

4 test tubes

Syringes

Tubes that connect to syringes

Stoppers that connect to tubes and fit into tubes

Test tube rack

Freezer

Ice bath

Dry hot bath

Thermometers

Scale

Measuring cylinders

Procedures:

1) Label 4 test tubes with the temperatures (0C, 20C, control, and 50C)

2) Measure 1g of yeast, 1g of sucrose, 35ml of water, and .1g of salt for each test tube

3) Mix all ingredients at the same time

4) Check and make sure stoppers and syringes are properly attached 

5) Push stoppers, tightly closing tubes

6) Set all tubes on the test rack

7) Let yeast begin cellular respiration for 5 minutes

8) Record a common baseline measurement for the test tubes

9) Put the test tubes to the corresponding temperatures

10) Record the measurement of air in the syringes every 2 minutes for 10 minutes

Results:

Temperatures	2mins	4mins.	6mins.	8mins.	10mins.
Control (Room temp.)	2	2.8	3	3	3
0 degrees C	2.2	2.6	2.8	2.8	3
20 degrees C	2.2	3.2	2.8	4	4.6
50 degrees C	2.2	4	6	9.4	12+

Graph:

Conclusion:

Our results showed that the tubes in higher temperatures had a higher amount of air in the syringe. Even though the results of the control were affected by an error of the syringe not being tightly closing the test tube, letting outside air in, the rest of our data proved and verified our hypothesis that cell respiration increases as temperature increases. The test tube placed in 0 degrees Celsius had little change in air. The test tube placed in 20 degrees celsius had some change in air but the one placed in 50 degrees celsius hot bath had the most change in air and exceeded the amount on the syringe. Cell respiration increased in the 50 degrees celsius test tube, effectively showing that temperature affects cell respiration by increasing molecular motion. Even though our hypothesis was verified, some errors were made that might of affected the results of the lab. We concluded that there was a leak in the test tube of the control. Also, our timing might not have been recorded at the same time.