ACTIVITY 9.2: Modeling cellular respiration: How can cells convert the energy in glucose into ATP?
Draw the overall process of cellular respiration starting with glucose and ending up with ATP production in the mitochondria. Include the steps of glycolysis, the citric acid cycle and oxidative phosphorylation
Be sure to include the following in your pathway:
ADP and Pi
Electron transport chain complexes I IV
Mitochondria and its membranes, cristae and matrix
H+ and H+ gradients
Chemiosmosis & Oxidative phosphorylation
Substrate level phosphorylation
Use your pathway diagram to answer the following:
1. The summary formula for cellular respiration is
C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy (ATP + heat)
At what stage(s) in the overall process is each of the reactants used?
At what stage(s) in the overall process is each of the products produced?
Electron transport chain (ETC)
ETC - ATP
2. In cellular respiration, the oxidation of glucose is carried out in a controlled series of reactions. At each step or reaction, a small amount of the total energy produced is released. Some of this energy is lost as heat but the rest is converted into other forms that can be used by the cell to make ATP or to drive an endergonic reaction
What is/are the overall function(s) of glycolysis?
What is/are the overall function(s) of the Krebs Cycle
What is/are the overall function(s) of oxidative phosphorylation?
1. Pyruvate (2)
2. ATP (2)
3. NADH (2)
4. CO2 (2) (transition step)
5. NADH (2) (transition step)
1. ATP (2)
2. NADH (6)
3. FADH2 (2)
4. CO2 (4)
1. ATP (32)
Are the components listed here USED or PRODUCED in:
The Krebs Cycle?
used & produced
ADP + Pi
4. If the Krebs cycle does not require O2, why does cellular respiration stop after glycolysis when no O2 is present?
The ETC creates a H+ gradient which allows for the import of pyruvate into the mitochondria i.e. the H+ gradient drives the import of pyruvate that happens during the transition step
5. How efficient is fermentation vs. aerobic/cellular respiration. Efficiency is the amount of useful energy (as ATP) gained during the process divided by the total energy available in glucose. Use 686 kcal as the total energy available in 1 mole of glucose and 8 kcal as the energy available in 1 mole of ATP
Efficiency in fermentation
Efficiency in cellular respiration
2 ATP during glycolysis x 7.3 = 14. 6 kcal of energy
14.6/686 = 2% efficiency
36 ATP made ( including glycolysis) x 7.3 = 263 kcal/mole
263/686 = 38% efficiency
32 from ETC x 7.3 = 234 kcal/mole
234/686 = 34% efficiency
6. Mitochondria isolated from liver cells can be used to study the rate of electron transport in response to a variety of chemicals. The rate of electron transport is measured as the rate of disappearance of O2 from the solution using an oxygen-sensitive electrode. How can we justify using the disappearance of O2 from the solution as a measure of electron transport?
O2 is the ultimate electron acceptor in the ETC
7. An active college-age athlete can burn more than 3,000 kcal/day in exercise.
a. If conversion of one mole of ATP ADP + Pi releases about 7.3 kcal, how many moles of ATP need to be produced per day in order for this energy need to be met?
b. If the molecular weight of ATP is 573, how much would the required ATP weigh in kilograms?
c. Calculate and explain your results below
a. 3000/7.3 = 411 moles of ATP
b. 411 X 573 = 235,503 g = 235 kg