Energy metabolism Introductory Biology, 9 September 2010 Donald Winslow References: Alberts et al Molecular Biology of the Cell, 5 th ed., Garland Science, NY; Ch. 2, Ch. 14. Hoefnagels Biology, 1 st ed., McGraw-Hill, NY; Ch. 4 (pp 80-89), Ch. 5 (pp , ), Ch. 6 (pp ).

Conservation laws & thermodynamics Conservation of matter Conservation of energy (1 st law of thermodynamics)‏ Different forms of energy Kinetic energy Potential energy Heat Electromagnetic radiation etc. 2 nd law of thermodynamics

2 nd Law of Thermodynamics Entropy increases in closed systems. Entropy is disorder. A closed system does not exchange energy or matter with anything outside it. Transition of energy from one form to another always results in a loss of useful energy. Automobile engine Incandescent light bulb

Objectives Describe how photoautotrophs use solar radiation to build organic molecules that store energy. Explain how respiration and photosynthesis relate to each other in terms of reactants, products, and energy flow. Describe a metabolic cascade, such as glycolysis, and explain the roles of specific enzymes. Explain the citric acid cycle, electron transport, and oxidative phosphorylation. Explain the roles of ATP, NADH, and NADPH.

Metabolism Catabolism – Cellular respiration 6O 2 + C 6 H 12 O 6 --> 6CO 2 + 6H 2 O + metabolic energy Anabolism – Photosynthesis 6CO 2 + 6H 2 O + solar radiation --> 6O 2 + C 6 H 12 O 6

Cellular respiration Glycolysis Citric acid cycle Electron transport chain Chemiosmotic phosphorylation

Glycolysis (a metabolic cascade) Glucose --> Glucose-6-Phosphate G6P --> Fructose-6-Phosphate F6P --> Fructose-1,6-Bisphosphate F16B --> Phosphoglyceraldehyde PGAL --> 1,3-Bisphosphoglycerate 13BG --> Phosphoglycerate PG --> Phosphoenolpyruvate PEP --> Pyruvate

Cellular respiration Glycolysis & fermentation Citric Acid Cycle Respiratory Electron Transport Chain

Mitochondria Aligned along microtubules Outer membrane, inner membrane Matrix, intermembrane space, cristae Respiratory electron-transport chain

Photoautotrophs Plants Algae Cyanobacteria Goat’s Rue in Door County, Wisconsin

Photosynthesis