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

2. I can explain how catabolic pathways yield energy by oxidizing organic fuels.
Learning target 1

3. 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

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

5. Cellular Respiration Overview
Occurs mainly in mitochondria (begins in cytoplasm)
Glycolysis
“Prep Step”
Krebs Cycle (Citric Acid Cycle)
Oxidative Phosphorylation & Chemiosmosis (ETC)

6. I can explain how glycolysis harvests chemical energy by oxidizing glucose into pyruvate.
Learning target 2

7. 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

9. 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+

10. I can explain how the citric acid (Krebs) cycle completes the energy yielding oxidation of organic molecules.
Learning target 3

11. Oxidation of Pyruvate to Acetyl CoA (“Prep Step”)
Preps pyruvate for Krebs Cycle (linking glycolysis and citric acid cycle)
Occurs in mitochondria
3 step oxidation process
Carboxyl group (COO) is removed from pyruvate
Releases 1 CO2 (per pyruvate)
Remaining 2C fragment is oxidized, producing acetate and NADH
Creates 1 NADH (per pyruvate)
Coenzyme A attaches to acetate, forming Acetyl CoA
Forms 1 Acetyl CoA (per pyruvate)

12. “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

13. 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

14. 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

15. Glucose is now completely oxidized

16. Count the carbons!