Energy Flow in the Life of a Cell

1. Energy Flow in Cells

5. Exergonic Reactions (a) Burning glucose (sugar): an exergonic reaction Activation energy needed to ignite glucose Glucose + O 2 Energy released by burning glucose C O 2 + H 2 O Energy content of molecules high low Progress of reaction

6. Exergonic Reactions Energy Released + + High Energy Reactants Low Energy Products OH O O CH 2 OH O O O O C O H H

7. Endergonic Reactions (b) Photosynthesis: an endergonic reaction Glucose Net energy captured by synthesizing glucose CO 2 + H 2 O Activation energy from light captured by photosynthesis Energy content of molecules high low Progress of reaction

8. Endergonic Reactions + Low Energy Reactants + High Energy Products OH O O CH 2 OH O O O O C O H H Energy Supplied

9. Coupled Reactions

10. Phosphorylation & ATP = =

11. ATP versus ADP: Structural Differences ~ DiPhosphate TriPhosphate ADP ATP High-energy Phosphate Bond OH P O O O P OH OH O ~ Ribose H 2 C H O H OH OH H H N HC N C C C CH N N NH 2 Adenine P OH OH O OH P O O O P O OH O ~ Ribose H 2 C H O H OH OH H H N HC N C C C CH N N NH 2 Adenine

12. Coupled Reactions within Living Cells

13. Electron Carriers

14. Metabolic Pathways A B C F G Enzyme 1 Enzyme 2 Enzyme 3 Enzyme 4 Enzyme 5 Enzyme 6 Initial Reactants Intermediates Final Products Pathway 1 Pathway 2 D E

15. Activation Energy: Controls Rate of Reaction Activation energy without catalyst Activation energy with catalyst Energy content of molecules high low Progress of reaction

17. Enzyme Regulation: Feedback Inhibition Enz. 5 D Enz. 4 C Enz. 3 B Enz. 2 A Enz. 1 Threonine (substrate) Isoleucine (end product) Feedback Inhibition Isoleucine inhibits enzyme 1 CH 3 C C COOH OH NH 3 H H CH 2 C C COOH CH 3 NH 3 H H CH 3

18. Enzyme Regulation: Allosteric Regulation & Competitive Inhibition Substrate Enzyme Active Site Allosteric Regulatory Site (a) Allosteric Regulatory Molecule Shape of active site changed (b) (c) Competitive inhibitor occupies active site

23. The end