1. Chapter 9: Cellular Respiration

2. 9.1: Catabolic pathways yield energy by oxidizing organic fuels
Living cells require transfusions of energy from outside sources to perform tasks
Energy flows into ecosystem as sunlight and leaves as heat
Chemical elements essential to life are recycled
Cellular respiration breaks down fuel to generate ATP, and the waste products become the reactants for Photosynthesis

3. Catabolic Pathways and Production of ATP
Organic compounds store energy in their arrangement of atoms
- enzymes help break down products to simpler waste products with less energy
One catabolic process, fermentation is a partial degradation of sugars that occurs without the use of oxygen

4. Catabolic Pathways and Production of ATP
Cellular Respiration- oxygen is consumed as a reactant with organic fuel
- 2 of 3 processes take place in mitochondria
- similar to combustion of gasoline
- CHO’s, proteins, and fats can combust and consume fuel

5. The Principles of Redox
Redox Reactions or Oxidation-reduction reactions deal with the transfer of one or more electrons from one reactant to another.
Oxidation-the loss of electrons from one substance
Reduction- the addition of electrons to another substance
Reducing Agent-the electron donor
Oxidizing agent- electron acceptor

6. Stepwise Energy Harvest via NAD+
Reactions do not occur all at once, but it steps to properly harness energy
- gas tank explosion doesn’t drive car
Glucose broken in a series of catalyzed steps by an enzyme
NAD+ - a oxidizing agent or coenzyme that will strip electrons along with a proton (hydrogen)
NADH is reduced form that is potential energy and can make ATP

7. Stages of Cellular Respiration
Glycolysis-breaks glucose into two molecules of a compound pyruvate
- cytosol of cell
- does not require oxygen
- catabolic

8. Stages of Cellular Respiration
Citric Acid Cycle- Completes the breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide
- mitochondrial matrix
- redox reaction transfers electrons and forms NADH
- Also referred to as the Krebs cycle

9. Stages of Cellular Respiration
Oxidative phosphorylation: electron transport and chemiosmosis
- inner membrane of mitochondria
-accounts for 90% of ATP generated by respiration

11. Substrate-Level Phosphorylation
ATP synthesis that occurs when an enzyme transfers a phosphate group from the substrate to ADP
- generates a smaller amount of ATP
- substrate is generated from catabolism of glucose

12. 9.2: Glycolysis harvests chemical energy by oxidizing glucose to pyruvate

13. Glycolysis
Glycolysis- (splitting of sugar) breaks a six-carbon sugar into two three-carbon sugars
3 carbon sugars are oxidized and remaining atoms form 2 molecules of pyruvate
10 steps in the reaction

15. Phases of Glycolysis
Energy investment phase – 2 ATP are spent in the initial break down of glucose to its first 5 intermediates
Energy Payoff phase – ATP is produced by substrate-level phosphorylation and NAD+ is reduced to NADH by electrons released from oxidation of food
- produces 4 ATP molecules
Net production is 2 ATP molecules

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