1. 7.1/7.2 Importance of Cellular Respiration & Glycolysis

2. Complementary Reactions
Photosynthesis: series of reactions that convert light into chemical energy to produce energy-rich glucose molecules.
Glucose can be used immediately or stored.
Cellular Respiration: series of reactions that release the energy stored in glucose (in the form of ATP)
CO2(g) + H2O(l) + energy  C6H12O6(s) + O2(g)
C6H12O6(s) + O2(g)  CO2(g) + H2O(l) + energy

3. Compare and Contrast

4. Intermediates
Oxidation-reduction (redox) reactions produce intermediate products used by cells to complete processes
LEO the lion goes GER
Photosynthesis: NADPH (reduced from of NADP+) and ATP
Cellular Respiration: NADH (reduced form of NAD+) and FADH2 (reduced form of FAD+)
Serve as electron carriers: transfer electrons through redox reactions
Energy released can be used to make ATP (attach ADP to Pi)

5. Cellular Respiration
Breaking down of large energy molecules of glucose into smaller molecules
The smaller you break them down, the more energy you can derive from the process
The energy released in cellular respiration is used to synthesize ATP
Glucose molecules must be converted into another form of energy (ATP) before it is useful to the body

6. ATP
Estimated 1 billion molecules of ATP in a human cell - continuously broken down into ADP and Pi and reformed
Most processes that require ATP energy can be placed into one of the following categories (Table 1 pg 206) - motion - transport of ions/molecules - building of molecules - switching reactions on and off - bioluminescence

7. Glucose
Our “blood sugar”: high energy content, small, highly soluble - ideal for transportation
Chemical bonds of reactant food molecules (glucose) broken during respiration
Break bonds = requires energy
New bonds = energy released
Respiration an energy-releasing process: more energy released during formation of product molecules
Single glucose molecule - 36% converted into energy of ATP - 64% released as heat

8. Types of Cellular Respiration
Aerobic cellular respiration: requires O2 and involves complete oxidation of glucose (produces 36 ATP) - Stage 1: glycolysis (cytoplasm) - Stage 2: pyruvate oxidation (mitochondria) - Stage 3: Krebs Cycle (mitochondria) - Stage 4: ETC and chemiosmosis (inner mitochondria)
Anaerobic cellular respiration: occurs in absence of O2 and glucose is not completely oxidized. - Stage 1: glycolysis (cytoplasm) - Stage 2: fermentation (cytoplasm)
2 types of anaerobic respiration: one produces ethanol, one produces lactic acid
NOTE: BOTH BEGIN WITH GLYCOLYSIS!!!

10. Aerobic cellular respiration: Overview

11. Stage 1: Glycolysis “sugar splitting” No oxygen required
Thus it is the first step for both aerobic and anaerobic respiration
Occurs in the cytoplasm
Starts with glucose (6-carbon sugar)
2 ATP molecules are used in the first stages of glycolysis (“investment phase”)
2 NAD+ removes H+ ions and forms 2 NADH
Later enough energy is released to form 4 ATP, which will be available to be used in cellular functions
Glycolysis produces TWO 3-carbon pyruvate molecules
Net production of 2 ATP

12. Glycolysis

13. Glycolysis Relatively inefficient
Only transfers about 2.2% of free energy available in glucose to ATP
Some released as heat, but remainder tied up in pyruvate and 2 NADH molecules
glycolysis

14. Glycolysis Review: Reactants: 1 Glucose 4 ADP 4 Pi 2 ATP 2 NAD+ 2 H+
Products:
2 Pyruvate
4 ATP (therefore, net gain of 2 ATP)
2 ADP
2 NADH