Monday, November 18, 2013

Cellular Respiration Lab

Purpose- The purpose of this experiment is to determine whether germinated or non-germinated seeds had a higher respiration.  We did this by determining the rate of respiration for the non-germinated seeds and then with the germinated seeds before and after having sat in cold water. We used temperature as variable to see if the results would differ.  We also tested glass beads to determine a control between the two.  This lab helped us to understand the process of respiration and what can potentially slow down this process.

Introduction- Cellular respiration is a multi- step metabolic process that produces energy by the oxidation of organic molecules. Humans and animals go though this process. This process is aerobic and anaerobic. Aerobic means it has oxygen and anaerobic means without oxygen. The reason it is anaerobic and aerobic is because one step is anaerobic and the other steps are aerobic.  The process starts with an organic molecule and oxygen and ends with carbon dioxide, water, and energy. An example of this is glucose going through cellular respiration C6H12O2 + 6O2 -> 6 CO2 + 6 H2O + Energy. This is also called a redox reaction. Redox reactions are the transferring of electrons. The name redox comes from a mixture of the 2 things happening in a redox reaction.  One substance in being reduced (gains electrons) and oxidation (losing an electron). The electrons are transferred with coenzymes. NAD+ is the oxidized state and NADH is the reduced state.  Cellular respiration  goes through 3 steps. The first step is glycolysis which is an anaerobic process. Glycolysis end products are 2 ATP and 2 NADH and 2 pyruvate. The 2 pyruvate are oxidized to become 2 acetyl CoA . The next step is called the Krebs or Citric Acid cycle. The Krebs cycle is named after the scientist who discovered it Hans Krebs. This cycle uses the 2 acetyl CoA. This means that this cycle is repeated. After the 2 times the end products are 6 NADH and 2 FAD2.The last step is oxidation phosphorylation it consists of the electron transport chain and chemiosmosis. The electron transport chamber helps gradually decreases the free energy. During this time H+ are being pumped across the membrane and it creates a H+ gradient. In chemiosmosis the flow of H+ helps power  ATP synthesis.Oxidation phosphorylation   creates 26- 28 ATP. After all the steps are complete  it should result in about 30-32 ATPs. In this experiment we will use these concepts to help us understand the CO2 release.

                                                        Glass beads 

                                                 Germinating barley seeds 
                                           Non germinating barley seeds 
                                               Cold germinating barley seeds 
             Germinating barley seeds 
                      Barley seeds

   CO2 chamber- calculated amount of CO2 being produced by seeds and glass beads. 

Methods- We picked out 25 glass beads and 25 barley seeds that were germinated and 25 seeds that were not germinated. The 25 glass beads were used for a control group. We then put 25 glass beads in the respiration chamber. We let the beads the glass beads sit for 10 minutes. After the ten minutes was up we started to take measurements of CO2, with a device that measures CO2 contents.  We recorded the data on our Vernier Lab quest . Next we performed the same steps from the glass beads to the germinating Barley seeds, non germinating barley seeds. Except the  germinating barley seeds that have been placed in a cold ice bath for ten minutes. 

Discussion- Germination causes a higher rate of respiration than the non-germinating peas. This is because a seed needs to have optimal conditions in order for it to germinate. These conditions are met through cellular respiration which provide the correct amount of energy for these reactions to occur. Non-germinating seeds are "dormant" and their energy is stored (this is why nuts and seeds have so many calories); therefore, they don't need as much energy to perform vital processes. The beads served as a control group because no cell respiration occurred. This allowed for certain factors such as pressure to be accounted for without having to directly control it.

Lower temperature slows down the respiration process. The rate at which a reaction occurs, increases with higher temperatures. The higher the temperature of a solution, the faster the molecules are moving in solution. There are more collisions between reacting molecules, and more of those collisions have the necessary kinetic energy required to break bonds and perform necessary function. Respiration is a chemical reaction that breaks down glucose into carbon dioxide and water, so it works in the same way. The higher the temperature, the more kinetic energy because of the molecules moving around, the more cellular respiration can occur.

Not maintaining a constant temperature in the water bath could have caused inaccurate results. Keeping the cold, germinating seeds at a constant temperature would've made the experiment more accurate. Putting the respiration chamber in an ice bath would be a good idea. 

Conclusion- We concluded from the lab that germinating peas that have been at room temperature or in a cold ice bath have a higher rate of cellular respiration. This is because when plants germinate, they are coming out of the seeds as sprouts and beginning to grow, thus needing to use up more oxygen. Seeds that are not germinating do not need as much oxygen because they are not beginning to grow. The germinating seeds that were placed in the cold ice bath had a slightly slower rate of cellular respiration than the germinating seeds at room temperature because the cold temperature slowed it down. The rate of respiration is faster in warmer temperatures. 

References- References-

Monday, November 4, 2013

Enzyme Catalyst Lab


2B) The purpose of this part of the lab was to determine the amount of hydrogen peroxide (H2O2) initially present in a 1.5% solution. We were testing the concept of establishing a baseline without adding catalase (enzyme) to the reaction mixture. The dependent variable is the hydrogen peroxide (H2O2), water, and H2SO4. The independent variable is the amount of KMnO4 used in the burette to get the solution a persistent pink or brown color. 

2C) The purpose of this part of the lab was to determine the course of an enzymatic reaction in a reaction. In order to do this, we needed to measure the amount of substrate disappearing over time increments of 10, 30, 60, 90, 120, 180, and 360 seconds. We were testing the concept of the amount of substrate decomposed in these time amounts. The dependent variable was the amount of hydrogen peroxide, yeast, and water that were combined in the beaker while the independent variable was the amount of time the reaction was allowed to take place before the KMnO4 was added to stop the reaction. 

        This lab deals with enzymes, catalyze, and the reaction of the two together. Enzymes are proteins produced by living cells, and a catalyst is a substance that speeds up the reaction and lowers reaction energy.  Enzyme catalyst connects to a site of an enzyme, lowering the amount of energy required to produce a reaction with the substrate.
In this experiment we used the titration method to determine the quantity of substances in many different types of solutions.This experiment will help us to observe how catalyst enzymes work to speed up the reactions and turn hydrogen peroxide into water and oxygen gas.  By letting these reactions take place for different amounts of time, we could compare and contrast which conditions and time limits cause more of a reaction and which cause less. WE LOVE ENZYMES!!!!  :)


2B) We tested a baseline as a comparison for the experiment. We mixed water, hydrogen peroxide, and sulfuric acid. After removing a 5 mL sample of the mixture and added KMNO4 until the pink color remained visible in the liquid.

2C) We had 7 different cups labeled with 7 different times (10, 30, 60, 90, 120, 180, 360 seconds).  In each cup we put the same amount of hydrogen peroxide, yeast, and acid; however, after adding the hydrogen peroxide and yeast, we controlled the amount of time we let the reaction take place. In order to stop the reaction we added sulfuric acid after a specific number of seconds. The times listed on the cups represented the amount of time we let the yeast and hydrogen peroxide react. Then, we removed a 5 mL sample and added KMNO4 until the pink color remained visible in the liquid. The longer we let the reaction take place, the less KMNO4 was needed in order to make the color stay.
Data from part 2C

Data used from part 2C
Graph 2.1

2B) In this experiment the level of KMnO4 the burette dropped from 27 ml to 24 ml. This means that the level of KMnO4 dropped 3.1 ml.  These results are important because the baseline is used in every experiment. The baseline is used too test the amount of H2O2 in a 1.5 solutions.

2C) In this experiment we want to test the rate of spontaneous conversion of H2O2 without an enzyme. We had to use the baseline again but this time the baseline difference between the initial and final reading is 3.7 instead of 3.1. It is different because we had to make a new baseline. The baseline is not supposed to sit for 24 hours. We have to account for the natural breakdown of H2O2. It can naturally breakdown but also external factors can make it breakdown more like enzyme and temperature change in the room. Without a enzyme only .6  ml has been decomposed. Using the formula (ml baseline - ml 24 hour / ml  baseline) X 100 we found out that 19.3 % has been decomposed. It makes sense that the number is low because there was no enzymes in the  experiment. The enzymes can help lower the activation energy.  Activation energy is how much energy it takes to start a reaction. H2O2 could have a high activation energy and that could be a reason why not a lot of H2O2 decomposed. I think the way that the experiment was set up it was good. It was beneficial that we all used the same 24 hour solution. It helps us standardize our results. If even all made our own 24 hour solution all of our results could be greatly varied, like we could mess up on the make up of the solution or how much time it spends sitting.

2D) In this experiment we tested the same reaction as the last experiment but instead of no enzyme we added enzymes to the experiment. In this experiment we see that as time progressive  the enzymatic rate lowered. The highest rate is the first in the first time interval (0-10) . It was the highest because iit had the highest catalysis amount and the most amount of H2O2 to decompose. The lowest rate was the last time interval  (180 -360) there are 2 possible reason why it is the lowest. One is the H+ content makes the solution more basic. This moves the solution away from its optimal ph, thus causing the enzyme to denature. Denaturing is when the enzyme becomes biologically inactive because the proteins begins to unfold. Another reason could be is that all the catalysis amount is at the lowest because all the enzymes are already being used.  This causes an inhibiting effect on reaction. Inhibiting is when the reaction is stopped or slowed down. If we were to lower the temperature it would still cause the enzyme to denature. Like ph, enzymes also have an optimal temperature if the temperature gets too low or too high it will denature. 


By performing this experiment we were able to determine the quantity of a substance in different solutions through the titration method. We also recorded the rate of how quickly the catalsye enzyme was able to convert Hydrogen Peroxide to water and oxygen gas, which helped us expand our knowledge of the importacne enzymes and how they function.


Titrating solutions

Yeast- catalyst used to start the reaction
Color of solution after being titrated 

All the solutions being set up to be timed with the catalyst