Lecture 5 Outline (Ch. 9)

I. Respiration Overview

II. Redox Reactions

III. NAD+/NADH

IV. Glycolysis

V. Pyruvate Oxidation

VI. Summary

Cellular Respiration

Overall purpose:

• convert food to energy

• animals AND plants

• complementary to photosynthesis

Cellular Respiration:(Exergonic)

Cellular Respiration

• 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)

Redox Reactions

• follow the H, e- move with them

Use “H rule” for reactions in this classReactant with more H’s = e donor, will be oxidized

Reactant with more O’s = e acceptor, will be reduced

ZH2 + O2 yields ZO + H2O

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

• transfer of e- to oxygen is stepwise

Redox Reactions

• e- moved by NAD/H (from niacin/vit B3)

• NADH carry e- (reduced!)

Where do e- come from?

• NAD+ not carrying e- (oxidized!)

Where do e- go?

• glucose NADH ETC O2 (makes H2O)

Redox Reactions

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?

1. glycolysis

• Steps of respiration:

3. Citric acid cycle

4. ETC & oxidative phosphorylation

Steps of Respiration

2. Pyruvate oxidation

4 CO2

2 CO2

1. Glycolysis

• 1 glucose (6C) 2 pyruvate (3C)

• Keep track of: - inputs/outputs

- Electron carriers

plus:

- ATP/ADP

Cellular Respiration

- CO2

- O2

• eukaryotes AND prokaryotes

ATP

ADP

1

Glucose

Glucose-6-phosphate

Glycolysis

2

Glucose-6-phosphate

Fructose-6-phosphate

Fructose-1, 6-bisphosphate

Dihydroxyacetonephosphate

Glyceraldehyde-3-phosphate

4

5

GlycolysisATP

ADP

2

2 ADP

2 ATP

Phosphoenolpyruvate

2 Pyruvate

10

Glycolysis

2 ATP

2 ADP 3 steps not shown

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

2. Pyruvate Oxidation (coenzyme junction) • 2 pyruvate (3C) 2 Acetyl CoA (2C)

Cellular Respiration

• pyruvate joins coenzyme A (from vitamin B5)

• 2 carbons lost (as CO2)

• 2 NAD+ 2 NADH

Where do the outputs go?

At homeMatch each Step Name with Energy Balance and Basic Reaction