Unit 9 Cellular Respiration p. 119

Cellular Respiration Uses the potential energy stored in the bonds of fuel molecules to produce ATP ATP then used for cellular work Fuel molecule- glucose Glucose is broken down into water, carbon dioxide and energy (ATP)

C 6 H 12 O 6 + 6O 2 --  6CO 2 + 6H 2 O + Energy Label the names of the molecules. Label the reactants and the products in your lab manual. Which of the reactants and/or products will we measure today?

C 6 H 12 O O 2 --  6CO 2 + 6H 2 O + Energy (ATP) We can measure the rate of the reaction by measuring the 1. Oxygen consumption Quantitative assay (test) reactant 2. Carbon dioxide production Qualitative assay product

Third experiment- Alcoholic Fermentation Form of anaerobic respiration Yeast cells break down glucose to produce ATP in the absence of oxygen Process used- glycolysis End product of glycolysis (pyruvate) is then reduced to either lactic acid or ethanol. –Much of the bond energy is still contained in these “waste” products. We will study alcoholic fermentation –Ethanol and carbon dioxide produced Measure amount of carbon dioxide produced.

Exercise 9.1 Oxygen consumption as a measure of metabolic rate Measure the rate of respiration (oxygen consumption) of a mouse. Respiration chamber Observe the movement of a soap bubble in a tube as the mouse uses oxygen in the chamber

1. Place 25 g of KOH in bottom of chamber to absorb exhaled carbon dioxide. (Don’t allow KOH to touch skin.) 2. Instructor will weigh animal and place in chamber. 3. Wet the inside of tube with water and place stopper in chamber. Seal the end of a tube with a drop of soap solution. You may have to work with this. 4. Use a stopwatch to record the time it takes for the bubble to move a set distance along the tube. Record 5 time intervals.

Calculate metabolic rate for mouse Record data in table 9.1 Final calculation is ml/O2/g/h Find an average for your five trials Compare to other groups Also, compare your metabolic rate to the rates for oxygen consumption in other animals (Table 9.2) –Prepare the graph on the handout and include your mouse data. I will check graph before you leave.

Ex. 9.2 Carbon dioxide production in plants –Measuring reactants or products (of aerobic respiration)? Compare the production of carbon dioxide in peas- –germinated –germinated-boiled.

Set up flasks as described in manual Boil one set of peas, the other will not be boiled. Incubate for 1 hour. (make sure stopper is on tight) After 1 hour, place the tube in a tube of phenol red. Remove stopper from thistle tube and pour 100 ml of tap water in. (Flush collected gas into tube of phenol red.) Observe any color changes in the phenol red pH indicator.

Analysis of Ex 9.2 Was this a quantitative or qualitative assay? In which set-up was carbon dioxide produced?

Structure of mitochondria The Krebs Cycle (citric acid cycle) and the electron transport chain take place in the mitochondria. View Figure 9.3 and the model of the mitochondrion in the lab. Identify these structures: –Inner membrane –Outer membrane –Crista –Location of ATP synthase molecules –Matrix Know the structures in the sketch on p125 AND on the model set up in the lab.

Exercise 9.3 Fermentation in yeast Fermentation is an anaerobic process –Only yields 2 ATP per glucose while aerobic respiration yields 36. In alcoholic respiration, the cells use glycolysis to produce ATP. The pyruvate molecules from glycolysis are reduced to ethanol.

1. Prepare 3 beakers with 0.5 grams of yeast and the appropriate glucose solution 2. Let stand for 5 minutes. 3. Transfer to a fermentation tube. Tilt tube to remove all the air from the neck. 4. Incubate at 37 C. Measure CO2 production at 10 minute intervals.