Biology Study GuideCh.6: Energy- Thermodynamics = study of energy changes- Forms of energy:o Potential energy = stored energyo Kinetic energy = energy of motiono Heat, Sound, electric current, light or radioactive radiation.o Kilocalories = units of heat used to measure energy.- Photosynthesis = stores light energy from the Sun as potential energy for use in other molecules.- LEO says GER = “Loss of E lectrons is Oxidation” says “Gain of Electrons is Reduction”- Laws of Thermodynamics and Free energyo Energy cannot be created or destroyedo Energy is lost as disorder increases.o Chemical reactions can be predicted based on changes in free energy. Endergonic chemical reactions absorb energy from surroundings. Exergonic reactions release energy to the surroundings.o Spontaneous chemical reactions require activation energy.- Adenosine triphosphate (ATP) = molecular currency used for cellular energy transactions.- Cells store and release energy in the bonds of ATP.- ATP hydrolysis drives endogenic reactions.- ATP cycles continuously.- An enzyme alters the activation energy of a reaction.- Active sites of enzymes conform to fit the shape of substrates.- Enzymes occur in many forms.- Environmental and other factors affect enzyme function.o Coenzymes are nonprotein organic molecules (e.g. vitamins) - Metabolism = the sum of all biochemical pathwayso Anabolic = build up molecules (require energy)o Catabolic = break down molecules (release energy)- Biochemical pathways organize chemical reaction in cells.- Biochemical pathways may have evolved in stepwise fashion.- Feedback inhibition regulates same biochemical pathways.Ch.7: How Cells Harvest Energy- Autotrophs (Plants, algae, and some bacteria) = use chemical energy.- Heterotrophs = live on the organic compounds autotrophs produce, using them as food.- Cells oxidize organic compounds to drive metabolism. Cellular respiration is the complete oxidation of glucose.o Aerobic respiration = uses oxygen as the final electron acceptor for redox reactions. o Anaerobic respiration = uses inorganic molecules as acceptors, and fermentationuses organic molecules.- Electron carriers play a critical role in energy metabolism.- Metabolism harvests energy in stages.- ATP plays a central role in metabolism.- Cells make ATP by two fundamentally different mechanisms.- Glycolysis converts glucose into two pyruvate and yields two ATP and two NADH in the process.- NADH must be recycled into NAD+ to continue respiration.- The Krebs cycle extracts electrons and synthesizes one ATP.- Glucose becomes CO2 and potential energy.- The electron transport chain produces a proton gradient.- The gradient forms as electrons move through electron carriers. Chemiosmosis utilizes the electrochemical gradient to produce ATP. ATP synthase is a molecular rotary motor.- The theoretical yield for eukaryotes is 30 molecules of ATP per glucose molecule.- Calculation of P/O ratios has changed over time.- Methanogens use carbon dioxide. Sulfur bacteria use sulfate. Fermentation uses organiccompounds as electron acceptors.- Catabolism of proteins removes amino groups. Catabolism of fatty acids produces acetylgroups.- A small number of key intermediates connect metabolic pathways. Acetyl-CoA has manyroles. - The earliest life-forms degraded carbon-based molecules present in the environment.- The evolution of glycolysis also occurred early.- Anoxygenic photosynthesis allowed the capture of light energy.- Oxygen-forming photosynthesis used a different source of hydrogen.- Nitrogen fixation provided new organic nitrogen.- Aerobic respiration utilized