How Cells Use Energy Chloroplast energy is first captured and stored as glucose Mitochondrion where cells break down glucose and make ATP release energy Autotroph makes their own energy Heterotroph don t make their own energy The 2nd law of thermodynamics the natural tendency to lose energy to heat over time helps explain the concept of energy capture and release Photosynthesis is an endergonic energy in reaction plants take in CO2 and build carbohydrates and give off oxygen Respiration is an exergonic energy out reaction animals take in oxygen breakdown carbohydrates and give off CO2 generally speaking the word respiration refers to the metabolic pathway that occurs in the mitochondrion where glucose is made into ATP Photosynthesis 6CO2 6H2O light C6H12O6 6O2 Respiration C6H12O6 6O2 6CO2 6H2O Energy Capture Where exactly is the energy that we re going to extract It is contained in the electrons in the chemical bonds of glucose The goal to harvest the energy in those electrons Energy extraction occurs in a series of steps Oxidation Reduction movement of electrons from one molecule to another Oxidation loss of electrons Reduction gain of electrons think of it as a gain of a negative charge thus reduction Redox both occurring together in a series The role of oxygen in all this the high energy electrons released harvested from glucose are attracted to or pulled toward oxygen The pull towards oxygen helps to drive the metabolic reaction Summary goal is to capture energy of glucose in molecules of ATP this movement of electrons occurs in a series of controlled steps energy of electrons is therefore captured in some intermediate molecules before final synthesis of ATP Some electron energy carrying molecules we ll encounter in photosynthesis NADP empty no electrons in oxidized state NADPH has gained electrons is in reduced state and now carrying energy In respiration electrons energy is captured in NADH In photosynthesis electrons energy is captured in NADPH Electron Transport A series of redox reactions where harvested electrons are captured as ATP oxygen is the final electron acceptor molecule O2 in the series this is why you breathe Von Helmont experiments 1648 showed that plants did not get biomass from soil Ingredients of photosynthesis carbon dioxide water energy Salient Point Photosynthesis turns CO2 into glucose Photosynthesis Photosynthesis takes carbon dioxide gas CO2 and builds it into a solid compound first flucose then starch and cellulose Photosynthesis involves two steps 1 light dependent reaction energy is stored on thylakoid membrane where chlorophyll and the light dependent reaction are located 2 light independent reaction CO2 stored energy glucose in stroma Two phases to photosynthesis photo harvesting of solar energy and storage into chemical bonds synthesis synthesis of glucose using the energy from photo Light Light has a dual nature exists as both particle and wave Light spectrum photosynthesis is driven by blues and reds green is reflected not absorbed
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