Cell Respiration Lab

Purpose

The purpose of this lab is to measure the amount of carbon dioxide released by cellular respiration by marbles, non-germinated peas, germinated peas, and germinated peas at a cool temperature.  

Introduction

Cell respiration is the process of oxidizing food molecules, like glucose, to carbon dioxide and water. It is represented by the equation: C₆H₁₂O₆ + 6O₂ + 6H₂O → 12H₂O + 6 CO_{2.  In cell respiration, chemical energy from "food" molecules is released and partially captured in the form of ATP. Carbohydrates, fats, and proteins can all be used as fuel for cell respiration, however glucose is the most common. Cells take the carbohydrate into their cytoplasm, and through a complex series of metabolic processes, they break down the carbohydrate and release energy in the form of ATP. When cells to go through cell respiration, they take in oxygen and release carbon dioxide.} 

First we put 25 marbles into the respiration chamber.

        

Then we put 25 non-germinating peas in the respiration chamber and recorded the amount of CO_{2 produced in 10 minutes.}

We then did the same process but with germinating peas.

We soaked the germinating peas in ice water for 5 minutes.

We blotted them dry and put them into the respiration chamber again.

Lastly, we tested the cold germinating peas in the respiration chamber for 10 minutes again.

Data:

Graphs:

Discussion

In this experiment, marbles, non-germinating peas, and germinating peas at different temperatures were tested for their particular rates of cell respiration. In testing the non-germinating peas in contrast to the germinating peas, data showed that germination greatly accelerated the rate of cell respiration. This shows a greater rate of metabolic activity in germinating peas versus non-germinating peas. The non-germinating peas showed very little activity, with only about .02 for the rate of respiration. When testing the peas dunked in cold water versus the peas that were at room temperature, the warmer peas showed an increase in respiration in contrast to the cold peas. The germinating peas respirate more than the dormant peas because the pea needs energy for the growth that is happening, something that is not needed in the dormant pea.  

Conclusion

This lab presents the different rates of respiration based on different organisms. It was found that

germinating peas respirate at a higher level than dormant peas.

Enzyme Catalysis Lab

Purpose:
The purpose of this experiment was to observe the conversion of hydrogen dioxide to water and oxygen gas by the enzyme catalase, and measure the amount of oxygen generated and calculate the rate of the enzyme-catalyzed reaction. We basically had to observe and understand the effects of changes in temperature, pH, enzyme concentration, and substrate concentration on the reaction rate of an enzyme-catalyzed reaction, and also to understand how environmental factors affect the rate of enzyme-catalyzed reactions.

Intro:
Enzymes are proteins produced by living cells. They are biochemical catalysts meaning they lower the activation energy needed for a biochemical reaction to occur. The substrate is the substance acted upon in an enzyme-catalyzed reaction, and it can bind reversibly to the active site of the enzyme. The active site is the portion of the enzyme that interacts with the substrate so that any substrate that blocks or changes the shape of the active sit effects the activity of the enzyme. The result of this temporary union is a reduction in the amount of energy required to activate the reaction of the substrate molecule so that products are formed. The enzyme is not changed in the reaction and can be recycled to break down additional substrate molecules. The enzyme used in this lab is catalase. One catalase function is to prevent the accumulation of toxic levels of hydrogen peroxide formed as a by-product of metabolic processes. The decomposition of hydrogen peroxide to form water and oxygen: 2 H2O2 → 2 H2O + O2 (gas) Without catalase this reaction occurs spontaneously but very slowly. Catalase speeds up the reaction notably.

Methods:

First we put 10 mL of 1.5% H2O2, and then added 1 mL of catalase extract and swirled it gently for 10 seconds. At 10 seconds,we added 10 mL of H2SO4. The same thing was done six more times but with intervals of 30, 60, 90, 120, 180, and 360 seconds before adding the H2SO4. 

 

 For each solution a 5mL sample was taken and put it into a fresh beaker and added drops of KMnO4 until the solution became colored.

Data

Finding our baseline (uncatalyzed) reading

*note our 10 second trial is miscalculated due to our error

Graph

Discussion

The rate of the reaction is calculated by measuring, over time, the disappearance of the substrate, which can be measured by seeing when the appearance changes of the product. The rate, in the experiment, is the highest from the initial to ten, because the hydrogen peroxide had been exposed to the air for the least amount of time. It's lowest rate was when the hydrogen had been exposed to the air longer. This is because the longer the hydrogen peroxide is exposed to air the more broken down it becomes, and therefore, weaker. The sulfuric acid has an inhibiting effect on the catalase's function because it causes the pH level in the solution to lower a considerable amount. Acidic solutions result in the protein structure of the enzyme to gain hydrogen ions which causes it to denature, which stops the reaction immediately. Lowering the temperature in this experiment would cause the reaction to slow down due to enzymes working best in normal temperature. If the temperature were lowered a larger amount, for example lower than 37 degrees celcius, it would be denatured and not be able to react anymore. Although this experiment was as controlled as possible, several things could have been controlled better. In some instances, too much KMnO4, resulting in a redo. Watching the reaction of the solution to the KMnO4 is not very controlled due to the fact that different people see different things. What one person sees as a change of color another may not. 

                                                                        Conclusion

This lab presents how changes in temperature, pH, substate concentration and enzyme concentration can effect the reaction rate of an enzyme catalyzed reaction. Our observations of the amount of oxygen produced in comparison to the rate of the enzyme catalyzed reaction showed how the environment can drastically effect the rate of the reaction. .