Aerobic Respiration and alcohol fermentation Bio 201 Lab # 7 Dr. Santos

How organisms obtain energy (ATP) for metabolism Three ways; Aerobic respiration (uses oxygen) C6H12O6 +6O2 -----6CO2 + 6H20 + 36/38 ATP Anaerobic respiration (no oxygen) Fermentation (partial breakdown of glucose); 2 types alcohol and lactic acid Alcohol fermentation (only produces 2 ATP) C6H12O6 -----2CO2 + 2C2H5OH + 2ATP

2 EXERCISES TO DO AEROBIC RESPIRATION EXERCISE QUESTION; Do germinating peas (growing) undergo more aerobic respiration than dried peas (dormant seeds)? Hypothesis;_______________________________________________________________ Lets set up an experiment to find out! Follow the procedure on pages 54-55 to set up your 2 respirometers! WE WILL MEASURE THE RATE AT WHICH OXYGEN IS CONSUMED!!!

PAGE 55 REVIEW QUESTIONS Once experiment starts, the peas will start to undergo aerobic respiration, they will use up oxygen gas. They will release carbon dioxide gas. The carbon dioxide will react with KOH to form a solid product, KHCO3

Exercise 2 Fermentation C6H12O6 -----2 Pyruvate molecules + 2ATP ------ 2CO2 + 2 acetaldehyde--------- - C2H5OH Mg+2 is an important cofactor needed by many of the enzymes involved in the above reactions! The chemical NaF is a respiratory inhibitor in that blocks fermentation by combining with Mg+2 . Without the cofactor, the enzyme changes shape and its noncompetitively inhibited by NaF. In this experiment you will set up 5 tubes, some will have NaF, which means these should have less fermentation, since you are adding the inhibitor! The tube with the most fermentation will produce the most Carbon dioxide gas!!!

Tube 1- 25 ml yeast /glucose +10 ml of water Tube 2- 25 ml yeast/glucose + 5 ml water and 5ml inhibitor (0.02M NaF) Tube 3- 25 ml yeast/glucose + 5 ml water and 5ml inhibitor (0.2M NaF) Tube 4- 25 ml yeast/glucose + 5 ml water and 5ml cofactor (0.2M MgSO4) Tube 5- 25 ml yeast/glucose + 5 ml water and 5ml cofactor (0.02M MgSO4) Incubate for 1 hour! Follow procedure on Page 57

What is expected? Tube 1 = + reaction Tube 2 = less fermentation than tube 1 since it has the inhibitor Tube 3 = even less than tube 2 since you added a higher concentration of the inhibitor Tube 4 = very good reaction, more than 1 since you added the cofactor! Tube 5 = very good reaction, lots of gas!

Review 1- glucose is the starting compound for both aerobic respiration and fermentation 2- germinating seeds take up oxygen 3- carbon dioxide builds up throughout positive reactions 4- the dry seeds are not undergoing aerobic respiration (dormant) 5-the KOH reacts with the carbon dioxide produced forming KHCO3 6- If we performed the experiment without the KOH, the higher level of carbon dioxide will not interfere with the change of volume of gas in the respirometer for the amount of oxygen consumed.