1. Intro to Cellular Respiration, Glycolysis & Krebs Cycle
Chapter

2. Review Ecology (Unit 2) Cellular Biology (Unit 4)
Heterotrophs get free energy by eating other organisms
Autotrophs make their own free energy from the sun
Cellular Biology (Unit 4)
Mitochondria are specialized organelles for energy capture and transformation

3. Catabolic pathways yield energy by oxidizing organic fuels
Section 9.1

4. Cellular Respiration C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy (ATP)
Type of coupled oxidation-reduction (redox) reaction
OIL RIG
Oxidation Is Losing electrons
Reduction Is Gaining electrons

5. Electron Carrier Molecules
B-vitamin coenzymes
NAD+ + 2H → NADH + H+
FAD + 2H  FADH2
reduced form
oxidized form
reduced form
oxidized form

6. Cellular Respiration Overview
GOAL: produce ATP (usable, free energy for the cell)
Occurs mainly in mitochondria (begins in cytoplasm)
Glycolysis
“Prep Step”
Krebs Cycle (Citric Acid Cycle)
Oxidative Phosphorylation & Chemiosmosis (ETC)

7. Addition of a Pi to ADP happens 2 ways
Substrate level phosphorylation
Addition of phosphate group directly without a proton gradient and ATP Synthase
Enzyme-catalyzed reaction transfers Pi to ADP
Found in glycolysis and Krebs cycle
Oxidative phosphorylation
Using proton gradient created by ETC in cristae membrane to make ATP
ETC + Chemiosmosis = oxidative phosphorylation

8. Glycolysis harvests chemical energy by oxidizing glucose to pyruvate
Section 9.2

9. 1. Glycolysis “glykos” = sweet; “lysis” = split apart
Occurs in cytosol
Aerobic or anaerobic process
Glucose is oxidized into 2 pyruvate
Requires 2 ATP to get started
Produces 4 ATP (net gain 2 ATP)
Produces 2 NADH

11. Summary of Glycolysis
One glucose (6C) converted into two pyruvates (3C)
Net yield of 2 ATP
2 NAD+ are reduced into 2 NADH & 2 H+

12. After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules
Section 9.3

13. Oxidation of Pyruvate to Acetyl CoA (“Prep Step”)
Preps pyruvate for Krebs Cycle (linking glycolysis and citric acid cycle)
Pyruvates are transported into the mitochondria
3 step oxidation process
Each pyruvate
Releases 1 CO2 (2 total per glucose)
Makes 1 NADH (2 total per glucose)
Sends 1 Acetyl CoA to Krebs Cycle

14. “Prep” Step Summary Started with 2 pyruvates Ended with:
2 CO2 released to air,
2 NADH that will go to ETC, and
2 Acetyl CoA molecules (2 C) that will move on to Krebs Cycle in the mitochondrial matrix

15. 2. Krebs Cycle (AKA Citric Acid Cycle)
Complete oxidation of glucose
Cycle because it occurs twice – once for each Acetyl CoA
8 step pathway occurring in mitochondrial matrix
Each catalyzed by specific enzyme
Step-wise catabolism of 6C citrate molecule
All remaining H, O, and C from glucose released

16. Krebs Cycle Summary At the end of 2 turns of the Krebs cycle:
6 NADH are generated
2 FADH2 are generated
2 ATP are generated
4 CO2 are released
If the yield is only 2 ATP, then why?
Value of NADH and FADH2
Krebs cycle produces large quantities of these electron carriers, which are reduced molecules and store energy that will go to the ETC
ETC will produce mass ATPs

17. Glucose is now completely oxidized

18. Count the carbons!