Ap Biology Chapter 9 notes

Topics: Cellular respiration, Adenosine triphosphate, Glycolysis Pages: 7 (1336 words) Published: December 10, 2013
AP Biology, Chapter 9
Cellular Respiration and Fermentation

Life is Work

9.1 Catabolic pathways yield energy by oxidizing organic fuels
Catabolic Pathways and Production of ATP
1. Distinguish fermentation and cellular respiration.
Partial degradation of glucose
Uses no O2
Yields some ATP
Cellular respiration
Complete degradation to CO2 and H2O
Requires O2 = aerobic
Yields much more ATP
2. Describe the summary equation for cellular respiration. Also note the specific chemical
equation for the degradation of glucose.
Organic compounds + O2 è CO2 + H2O + energy
C6H12O6 + 6O2 è 6CO2 + 6H2O + energy (ΔG = -686 kcal/mol)
Redox reactions: Oxidation and Reduction
The Principle of Redox
4. Define oxidation and reduction.
Oxidation = loss of electrons; really the increase in oxidation number
Reduction = gain of electrons; really the decrease in oxidation number
5. Explain how redox reactions are involved in energy exchanges.
When electrons are transferred, energy is released or stored
Ex. electrons transferred to oxygen fall to lower energy states
Oxidation of Organic Fuel Molecules During Cellular Respiration
6. Explain why organic molecules that have an abundance of hydrogen are excellent cellular fuels.
Electrons are shared very equally between H and C
Equal sharing means high energy
Transfer to oxygen releases the energy
Stepwise Energy Harvest via NAD+ and the Electron Transport Chain
7. Describe the role of NAD+ and the electron transport chain during respiration.
NAD+ + 2H (with their high-energy electrons) è NADH + H+
NADH passes high energy electrons to the top of the electron transport chain
As electrons flow, H+ is pumped across the inner mitochondrial membrane
O2 accepts the low-energy electrons at the end of the chain
8. Describe the function of a dehydrogenase.
Removes high energy electrons and accompanying hydrogen
Adds them to a cofactor è NAD
The Stages of Cellular Respiration: A Preview
9. Describe the localizations and most important results for the stages of cellular respiration.
Glucose è 2 pyruvate + 2ATP + 2 NADH
Pyruvate oxidation
Mitochondrial matrix in eukaryotes, cytoplasm in prokaryotes
Pyruvate è AcetylCoA + CO2 + NADH
Citric acid cycle cycle
Mitochondrial matrix in eukaryotes, cytoplasm in prokaryotes
Pyruvate è 3CO2 + 3NADH + FADH2 + ATP
Electron transport system (ETS) + chemiosmosis = oxidative phosphorylation
Mitochondrial inner membrane, bacterial plasma membrane
NADH + FADH2 used to make many ATP
10. Contrast oxidative and substrate-level phosphorylation.
Both make ATP
Uses the energy of a H+ gradient
ETS pumps H+, oxygen accepts low energy electrons
Substrate-level: high E phosphate transferred directly to ADP

9.2 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate
11. Describe how the carbon skeleton of glucose changes as it proceeds through
Six-carbon è 2 three-carbon
Glucose è pyruvic acid + energy
Energy Investment Phase
12. Explain why ATP is required for the preparatory steps of glycolysis.
Adds energy to glucose molecule
Glucose + 2ATP è fructose 1,6-bisphosphate + 2ADP + 2Pi
Breaks more easily
F1,6P è 2 glyceraldehyde 3-phosphate
Energy Payoff Phase
13. Identify where sugar oxidation, substrate-level phosphorylation, and the reduction of
NAD+ occur in glycolysis.
Sugar oxidation/NAD+ reduction
Performed by triose phosphate dehydrogenase
2 glyceraldehyde phosphate è 2 1,3-bisphosphoglycerate + 2 NADH
Substrate-level phosphorylation
2 1,3-bisphosphoglycerate + 2 ADP è2 3-phosphoglycerate + 2 ATP
2 3-phosphoglycerate è 2 phosphoenolpyruvate...
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