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Lecture Biology - Chapter 8: Cellular respiration

In this chapter: Write the overall reaction for glucose breakdown and show that it is a redox reaction; discuss the role of oxidation-reduction enzymes; state the four phases of cellular respiration and tell where each occurs in the cell; contrast the energy-investment step of glycolysis with the energy-harvesting steps;. | Cellular Respiration Chapter 8 Respiration Organisms can be classified based on how they obtain energy: autotrophs: are able to produce their own organic molecules through photosynthesis heterotrophs: live on organic compounds produced by other organisms All organisms use cellular respiration to extract energy from organic molecules. Respiration Cellular respiration is a series of reactions that: -are oxidations – loss of electrons -are also dehydrogenations – lost electrons are accompanied by hydrogen Therefore, what is actually lost is a hydrogen atom (1 electron, 1 proton). Respiration During redox reactions, electrons carry energy from one molecule to another. NAD+ is an electron carrier. -NAD accepts 2 electrons and 1 proton to become NADH -the reaction is reversible Respiration During respiration, electrons are shuttled through electron carriers to a final electron acceptor. aerobic respiration: final electron receptor is oxygen (O2) anaerobic respiration: final electron acceptor is an inorganic molecule (not O2) fermentation: final electron acceptor is an organic molecule Respiration Aerobic respiration: C6H12O6 + 6O2 6CO2 + 6H2O DG = -686kcal/mol of glucose DG can be even higher than this in a cell This large amount of energy must be released in small steps rather than all at once. Respiration The goal of respiration is to produce ATP. -energy is released from oxidation reaction in the form of electrons -electrons are shuttled by electron carriers (e.g. NAD+) to an electron transport chain -electron energy is converted to ATP at the electron transport chain Oxidation of Glucose Cells are able to make ATP via: 1. substrate-level phosphorylation – transferring a phosphate directly to ADP from another molecule 2. oxidative phosphorylation – use of ATP synthase and energy derived from a proton (H+) gradient to make ATP Oxidation of Glucose The complete oxidation of glucose proceeds in stages: 1. glycolysis 2. . | Cellular Respiration Chapter 8 Respiration Organisms can be classified based on how they obtain energy: autotrophs: are able to produce their own organic molecules through photosynthesis heterotrophs: live on organic compounds produced by other organisms All organisms use cellular respiration to extract energy from organic molecules. Respiration Cellular respiration is a series of reactions that: -are oxidations – loss of electrons -are also dehydrogenations – lost electrons are accompanied by hydrogen Therefore, what is actually lost is a hydrogen atom (1 electron, 1 proton). Respiration During redox reactions, electrons carry energy from one molecule to another. NAD+ is an electron carrier. -NAD accepts 2 electrons and 1 proton to become NADH -the reaction is reversible Respiration During respiration, electrons are shuttled through electron carriers to a final electron acceptor. aerobic respiration: final electron receptor is oxygen (O2) anaerobic .