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)

C6H12O6 + 6O2 -- 6CO2 + 6H2O + 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?

C6H12O6 + 6 O2 -- 6CO2 + 6H2O + 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 manualBoil 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

solution2. 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.