Cell Energetics Study Guide

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Cellular Energetics Study Guide

1. Overall Metabolism
a. Oxidation – a molecule LOSSES hydrogen, energy is RELEASED

b. Reduction – a molecule GAINS hydrogen, energy is GAINED and stored (the more reduced a molecule is, the more energy is stored in its COVALENT BONDS) *** Always occur in a coupled pair (RED-OX)***

c. Electron Carriers
i. Oxidizing Agents: are REDUCED to OXIDIZE another molecule 1. NAD+ - oxidizes glucose to 2 pyruvate in glycolysis, oxidizes pyruvate to CO2 in the Kreb’s cycle (gets reduced to NADH) 2. NADP+- oxidizes H2O to O2 during the Light Dependent Reactions of photosynthesis, final electron acceptor from chlorophyll (PSI) (gets reduced to NADPH) 3. FAD+- oxidizes NADH to NAD during glycolysis and transported to the mitochondrion (gets reduced to FADHs) ii. Reducing Agents: are OXIDIZED to REDUCE another molecule 4. NADH- reduces 2 pyruvate to 2 lactic acid in fermentation, reduces O2 during the respiratory chain (gets oxidized to NAD) *CANNOT pass through the mitochondrion* 5. NADPH- reduces CO2 to form carbohydrates (Calvin Cycle) in the Dark Reactions of photosynthesis (gets oxidized to NADP) 6. FADH2- reduces O2 during the respiratory chain (gets oxidized to FAD) *CAN pass through the mitochondrion*

2. Phosphorylation: Formation of ATP (ADP + P ATP)
d. Substrate-level: direct enzymatic transfer of a phosphate to ADP * Only occurs during glycolysis when O2 is not needed to function * Only a small amount of ATP is produced this way

e. Electron Transfer /Chemiosmosis: the movement of protons (H+) down a concentration gradient through ATP synthase that can HARNESS THE ENERGY OF THAT GRADIENT (proton-motive force) to bond ADP and phosphate to create ATP through oxidative phosphorylation * Occurs during the Light Dependent Reaction

* 90% of ATP is produced this way

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