1. Phenol red changes color twice in the photosynthesis experiment. At the end of the experiment, the phenol red in the Elodea tube placed been under the light will be a different color than the Elodea tube wrapped in aluminum foil. Explain each of the following: A) Why does Phenol Red first change from Red to Yellow, and what caused this to happen? B) Why does Phenol Red change from Yellow back to Red in one of the Elodea tubes? C) What specific compound causes this 2nd color change? D) Which specific metabolic cycle is involved in the 2 color change, and what is produced from this cycle that is important for the plant? 2. Based on the topics covered in the lectures and in the lab discussion, fully explain why yeast must go through Fermentation when there is no O: available (do not use terms like "Electron Recycling"). What happens During and then After Glycolysis that is critical for yeast to survive without oxygen? +Lab-03 OL Fermentation & Respiration 20-3.docx 3. Alcohol is made in sealed containers (no O). BRIEFLY discuss how Energy is created in EACH of the Three Cycles that would occur if the yeast containers were left open to air for the entire experiment. Do Not explain it using terms like "Aero- bic/Anaerobic" or "Cellular Respiration/Fermentation". Do not explain fermentation or discuss what yeast "Would Not Do". 4. Why does it take more drops of NaOH to neutralize the solution when you breath into the water After Exercising, than it does Before Exercising? 5. During the lab, there were gas bubbles created in several of the six compounds. Without a detailed explanation of Fermentation, Explain in simple terms: A) Why ARE yeast able to produce CO; from Sucrose? B) Why are yeast NOT able to produce CO; from Lactose? +Lab-03 OL Fermentation & Respiration 20-3.docx ==== Discussion === Anaerobic Fermentation During glycolysis NAD picks up two electrons, converting it to NADH. If oxygen is available, that NADH is processed in the mitochondria. If Oz is not available, the ETS cannot continue, and the available NAD' will be used up during glycolysis. CYTOPLASM Glycolysis Anaerobic H- NAD → NADH Becomes oxidized Q-0+2H NADH Acetyl CoA CA Pynl (TCA) Cycle MADH FACH ETS Oxidative Phosphorylation Becomes reduced NAD +2H + 20 NADH+H (carries 2 electrons) NAD is restored anaerobically through fermentation. This converts Pyruvate to Lactic Acid in Animal cells, or to CO; & Ethyl Alcohol (Ethanol) in Yeast. ATP is not directly produced during fermentation, but it allows glycolysis to continue by regenerating NAD'. Cells can produce some ATP through fermentation, but not nearly as much as they would using Oz in aerobic respiration. Glucose H-C-OH CH₂ 2 Ethanol 2 ADP 2 2 ATP 2 NAD 2 NADH +21 c-o сн 2 Pyruvate CH, 2 Acetaldehyde This experiment will test whether or not yeast have specific en- zymes to ferment certain mono, di, and polysaccharides. We can determine if fermentation occurs by observing an increase in the size of a gas bubble. This allows us to see if CO2 is produced. If we place a small test tube (filled with solution), into a larger test tube, and then invert the tubes, we can limit the amount of oxygen that is available to the yeast. Aerobic Respiration Aerobically, glucose is completely oxidized to CO2 and H2O. CHO + 60 6 CO2 + 6 HO As we breathe, O; and CO; are exchanged in our lungs. In this part of this lab we will measure the amount of CO; in your breath while you are resting, and then again after you have exer- cised. Exercising should increase your metabolism, and there- fore increase the amount of CO; in your breath. Phosphorylation Phosphorylation Phosphorylation When CO: bubbles through water a small amount of carbonic acid is formed, making the solution acidic. By measuring the number of drops of NaOH it takes to neutralize the acid, we can compare the amount of CO: you breathe out while you are calm vs. the amount of CO2 you breathe out after exercising. Photosynthesis Here, we test photosynthesis by adding Elodea to a phenol red solution, and then placing it under a light, or in a dark setting. Phenol Red is a pH indicator that is red in basic solutions and yellow in acidic solutions. You will breathe into the phe- nol red solution causing it to become yel- lowish (because of CO:). Photosynthesis is essentially the reverse of cellular respiration. Plants use CO; & light during photosynthesis to produce sugars, while giving off oxygen. After breathing into the phenol red, we will see if placing Elodea under a bright light can cause the solution to become more basic. See the Lectures & PowerPoint slides for complete discus- sions of the three major cycles in Cellular Respiration, the two cycles in Photosynthesis, and why cells go through Fermenta- tion. Understand how each applies to this lab. LIGHT REACTIONS NAD ADP -B Photosystem I Photos CALVIN CYCLE COP NADPH Lab-03 OL Fermentation & Respiration 20-3.doc