Cellular Respiration In Crickets Lab Report

Principles of Cellular Respiration

Ashley Flannigan
November 5th, 2013
Professor Ryan
BSC2010 Lab
Fall 2013
2220
ABSTRACT Students in a Biology 1 lab class constructed an experiment on Cellular Respiration by investigating the effects of temperature on crickets’ metabolic rate. By following the following procedures out of the Lab Manual, the students were able to find an almost accurate representation of the crickets’ cellular respiration rate under various temperatures in order to produce CO2. The crickets used in the experiment provided a prime example of how ectothermic critters use heat as their source of energy to metabolize their food.

INTRODUCTION PAGE A perpetual source of energy is a vital role in
all organisms to preform their metabolic functions. The precise process in which extracts energy from the following organic nutrients: proteins, carbohydrates, and fats are expended as fuel to form adenosine triphosphate (ATP). This process is cellular respiration, which is also referred to as aerobic respiration involves both aerobic and anaerobic respiration that occurs in the mitochondria of a cell. There are three stages of cellular respiration which can also be considered, energy harvesting. The first stage of cellular respiration is glycolysis, and also means, “sugar splitting.” Although, there isn’t much energy or ATP produced from this stage. The main purpose of glucose is to take one single glucose molecule and break it down into two molecules of a pyruvic acid, which is a three-carbon molecule. If the cell is not equipped with oxygen, then the fermentation process is engaged. In the fermentation process the pyruvate molecule is converted into ethanol or lactic acid. The fermentation process wasn’t administered in the experiment since the crickets required air to breathe. In order for the Krebs cycle or Citric Acid Cycle, which is the second stage of cellular respiration to occur it needs to acquire ATP and NADH. Within this stage of cellular respiration, the pyruvate molecules convert into acetyl CoA. This happens when the carbon dioxide exits the pyruvate and the NAD+ turns into NADH. Citrate is then created when the acetyl CoA merges with the oxaloacetate from the first cycle of the citric acid cycle and turning the citrate into isocitrate. Shortly after that happens, the isocitrate becomes oxidized to succinyl CoA, leaving the products of carbon dioxide and NADH2+. Then the succinyl CoA release the coenzyme A and phosphorylates the ADP into ATP. The succinate is then oxidized to create fumarate, which then converts the FAD into FADH2. The fumarate is then hydrolyzed to create malate. Finally, the malate is then oxidized to create oxaloacetate, which reduces the NAD+ into NADH2+. This cycle process continues for a total of two cycles to produce six NADH2+, two FADH2, and two ATP. The third and final stage of the cellular respiration process is the electron transport chain (ETC). This is where most of the ATP is produced and is only administered when oxygen is available. The electron transport chain is a sequence of molecules, which are located in the mitochondrial inner membrane. Just before attaining the ETC, NADH and FADH2 the electron carriers become oxidized by other molecules in the chain. By accepting the previous electrons in the citric acid cycle reduces both, the NADH and FADH2 of those electron carriers. The final electron acceptor in the electron transport chain is oxygen. The movement of the electrons within the ETC delivers an adequate amount of energy to power the movement of hydrogen ions proceeding to the three ETC protein complexes, from the middle of the mitochondria to the outer area. These ions move down the concentration and charge their gradient, which moves them back into the middle of the mitochondria and through the ATP synthase. The ATP synthase drives the production of ATP from the ADP and phosphate. Finally, the oxygen found in the middle of the mitochondria accepts the hydrogen ions and the ATP to form water. The equation for cellular respiration is below:
C6H12O6 + 6O2 6CO2 +6H2O + Energy (ATP) The question of this experiment is how does temperature affect the rate of cellular respiration in crickets.
Logically what should happen as the temperature increases, the molecules would have more movement and activity. As the temperature decreases the molecules would have less movement and a decrease in activity. Therefore, a logical prediction would be that the change in the cellular activity which would indicate the change in temperature. The students’ biology book’s definition of ectothermic is “referring to organisms for which external sources provide most of the heat for temperature regulation.”(Campbell, 2011) So in other words, these crickets use the sun for their external source of energy instead of breaking down food with their
metabolism.

MATERIALS AND METHODS The first part of the cellular respiration experiment. The students gathered and set up the computer along with the Vernier CO2 Gas Sensor. While one of the students logged on to the Biology with Vernier within the Logger Pro folder on the computer, then modified the length from five minutes to 3 minutes of the data being collected. An alternative student was weighing the empty respiration chamber on the balance and then had the time of her life or a challenge obtaining those ten crickets to put them in the empty respiration chamber. After all of the ten crickets were placed into the respiration chamber, they were weighed. One of the students took both of the recorded weights and subtracted them to get the total mass of the crickets. Once the one student that obtained a large beaker filled with ice to set up the first of the seven water baths got back. Another student quickly placed a thermometer in the large beaker of ice to take the actual temperature, which was 4 degrees Celsius. Then a student placed the CO2 gas sensor gently in the top respiration chamber full of crickets and placed it within the large beaker full of ice. All of the students waited three minutes before calculating the carbon dioxide for another three minutes on the Logger Pro program. Once the three minutes was over one of the students detached the CO2 sensor from the respirator chamber, which was previously removed and dried from the beaker full of ice, then covered with a paper towel so the crickets wouldn’t escape. The same student used the paper towel to wave air into the respiration chamber, which would help free the carbon dioxide and allow the crickets to recover for a four to five minute period. The recovery period is for the crickets to resume to their natural respiration rate, considering the crickets looked dead. Once the first bath was over we cleaned and replaced the large beaker with a clean room temperature large beaker. The second water bath consisted of almost the same routine, except we replaced the ice with a hand full of ice along with 300 mL of water. The students continued to dump water out and add more ice, and then water until they reached the 15 degrees Celsius was obtained. The students reattached the CO2 sensor and submerged the respiration chamber in the 15 degree Celsius water while holding the neck of the chamber. All of the students waited the three-minute grace period for the crickets to take the full affect of the temperature of the water. After waiting for three minutes the carbon dioxide concentration data was collected for another three minutes. After the three minutes was over the students dried and removed the respiration chamber was removed along with the CO2 sensor and carefully placing a paper towel to cover the escape exit for the crickets. One of the students waved air into the chamber so the crickets could recover to their normal state. The third, fourth, fifth, sixth, and seventh water baths used the same procedures as the second bath. The only differences were the various temperatures of water, which were the room temperature (25 degree Celsius), 30 degrees Celsius, 35 degrees Celsius, 40 degrees Celsius, and 45 degrees Celsius. Finally, the students needed to determine the rate of respiration. One of the students was on the computer looking at the graph that was determined by the Vernier CO2 Gas Sensor and the Vernier computer program. While the student looked at the graph of the respiration rates, they needed to determine where the data value began to increase. The student clicked on the Linear Fit button to perform the linear regression and recorded the slopes of the various water baths. This process was done for all of the various water baths. After the experiment was over the students cleaned their work area, released the 10 crickets to the cage in which they had come from and proceeded to finish the rest of the lab work.

RESULTS
Suggested Temperature (Degrees Celsius)
Actual Temperature (Degrees Celsius)
Slope (ppm/min)
Respiration rate (ppm/min/g)
Ice (approx. 4 degrees Celsius)
4 degrees Celsius
158.1
42.73
Cold Water Bath (approx. 15 degrees Celsius)
15 degrees Celsius
1006
271.89
Room Temp (approx. 25 degrees Celsius)
25 degrees Celsius
307.4
83.08
30 degrees Celsius
30 degrees Celsius
415.6
112.32
35 degrees Celsius
35 degrees Celsius
371
100.27
40 degrees Celsius
38 degrees Celsius
271
73.24
45 degrees Celsius
42 degrees Celsius
512.4
138.49
Table 1. Respiration rates vs. the various temperatures for individual group the students used in the experiment on the crickets.

Figure. 1 This graph shows respiration rate over a three minutes time in the various degree Celsius temperatures.

DISCUSSION/CONCLUSION Unfortunately, the students’ results display an extent of experimental errors. The students’ temperatures were close to the actual temperatures, which could conclude inaccurate results. The first CO2 sensor the students used was faulty, there is a possibility of the second CO2 sensor was as well. The CO2 sensor might not have been sealed tight on the respiration chamber, which would give false results. Another error that could have occurred was how far the respiration chamber was submerged in the water baths, which wouldn’t allow the crickets to acclimate to the different temperatures before the CO2 was tested. Some of the results do show that as the temperature increase so does the crickets’ respiration rate and the amount of carbon dioxide. The crickets’ bodies are able to tolerate diverse temperatures depending on the volume of warmth obtained from their environment, which concludes that they are ectotherms. Therefore, the crickets used the heat absorbed as the energy source for their bodies to metabolize and function. In other words, the more heat the crickets absorbed the more energy for their cells to work and respire. Which can fully explain why the crickets highest respiration rate occurred when the crickets were placed in the high degree of water of 42 degrees Celsius. This also, gives proof to the prediction in the introduction. Which also relates to the rate of respiration will decrease if the crickets are not delivered enough warmth.

REFERENCES:
1.
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