Cellular Respiration

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Unit 9

• Cellular Respiration
• p. 119

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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)

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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?

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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

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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.

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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

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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.
1. Place 25 g of KOH in bottom of chamber to
absorb exhaled carbon dioxide. (Dont allow KOH
to touch skin.)
2. Instructor will weigh animal and place in
chamber.
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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.

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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.

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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)
Remove stopper from thistle tube and pour 100 ml
of tap water in. (Flush collected gas into tube
of phenol red.)
After 1 hour, place the tube in a tube of phenol
red.
Observe any color changes in the phenol red pH
indicator.
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Analysis of Ex 9.2

• Was this a quantitative or qualitative assay?
• In which set-up was carbon dioxide produced?

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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.

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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.

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