Lecture 5 Outline (Ch. 9) Respiration Overview Redox Reactions NAD+/NADH Glycolysis Pyruvate Oxidation VI. Summary

Cellular Respiration Overall purpose: • convert food to energy • animals AND plants • complementary to photosynthesis

Cellular Respiration Cellular Respiration: (Exergonic) • catabolizes sugars to CO2 • requires O2 • at mitochondrion

Redox Reactions • as part of chemical reaction, e- are transferred • e- transfer = basis of REDOX reactions (reduction) (oxidation)

ZH2 + O2 yields ZO + H2O • follow the H, e- move with them Redox Reactions Use “H rule” for reactions in this class Reactant with more H’s = e donor, will be oxidized Reactant with more O’s = e acceptor, will be reduced ZH2 + O2 yields ZO + H2O • follow the H, e- move with them

Self-Check Reaction Molecule Reduced Molecule Oxidized ZH2 + O2 yields ZO + H2O CH4 + 2O2 yields CO2 + 2H2O C6H12O6 + O2 yields CO2 + H2O C8H18 + O2 yields CO2 + H2O Oxygen ZH2

Redox Reactions • transfer of e- to oxygen is stepwise

Redox Reactions • e- moved by NAD/H (from niacin/vit B3) • NADH  carry e- (reduced!) • NAD+  not carrying e- (oxidized!) Where do e- come from? Where do e- go? • glucose NADH ETC O2 (makes H2O)

In this equation NAD+ is converted to NADH. NAD+ + H+ + 2e-  NADH a. Which is the organic compound reactant? b. Did this reactant gain or lose electrons to become the product? c. Is this reactant oxidized or reduced to make the product?

• Steps of respiration: 1. glycolysis 2 CO2 2. Pyruvate oxidation 3. Citric acid cycle 4 CO2 4. ETC & oxidative phosphorylation

Cellular Respiration 1. Glycolysis • 1 glucose (6C) 2 pyruvate (3C) • Keep track of: - inputs/outputs plus: ATP/ADP - Electron carriers CO2 O2 • eukaryotes AND prokaryotes

Glycolysis Glucose-6-phosphate 2 Fructose-6-phosphate Glucose ATP 1 ADP 1 Glucose Glucose-6-phosphate 2 Glucose-6-phosphate Fructose-6-phosphate

Glycolysis ATP ADP Fructose- 1, 6-bisphosphate 4 5 Dihydroxyacetone Glyceraldehyde- 3-phosphate 4 5

Glycolysis 2 ADP 3 steps not shown 2 ATP 2 NAD+ 2 NADH 2 Phosphoenolpyruvate Pyruvate 10 2 NADH 2 NAD+

In glycolysis….. a. Is any O2 or CO2 used or produced? b. How many ATP are used? How many are produced? What is the NET ATP production? c. Where do the phosphates come from to make ATP? d. What are the outputs of glycolysis and where do these molecules go?

Energy production Mitochondria • energy from nutrients  ATP

Where do the outputs go? Cellular Respiration 2. Pyruvate Oxidation (coenzyme junction) • 2 pyruvate (3C) 2 Acetyl CoA (2C) • pyruvate joins coenzyme A (from vitamin B5) • 2 carbons lost (as CO2) Where do the outputs go? • 2 NAD+  2 NADH

At home Match each Step Name with Energy Balance and Basic Reaction