Chapter 10Overview: The Process That Feeds the BiosphereSlide 3Slide 4Slide 5LE 10-2Slide 7Concept 10.1: Photosynthesis converts light energy to the chemical energy of foodChloroplasts: The Sites of Photosynthesis in PlantsSlide 10LE 10-3Tracking Atoms Through Photosynthesis: Scientific InquiryThe Splitting of WaterLE 10-4Photosynthesis as a Redox ProcessThe Two Stages of Photosynthesis: A PreviewLE 10-5_1LE 10-5_2LE 10-5_3Concept 10.2: The light reactions convert solar energy to the chemical energy of ATP and NADPHThe Nature of SunlightSlide 22LE 10-6Photosynthetic Pigments: The Light ReceptorsLE 10-7Slide 26LE 10-8aLE 10-8bSlide 29LE 10-9aLE 10-9bSlide 32LE 10-9cSlide 34LE 10-10Excitation of Chlorophyll by LightLE 10-11A Photosystem: A Reaction Center Associated with Light-Harvesting ComplexesSlide 39LE 10-12Slide 41Noncyclic Electron FlowLE 10-13_1LE 10-13_2LE 10-13_3LE 10-13_4LE 10-13_5LE 10-14Cyclic Electron FlowLE 10-15A Comparison of Chemiosmosis in Chloroplasts and MitochondriaLE 10-16Slide 53LE 10-17Concept 10.3: The Calvin cycle uses ATP and NADPH to convert CO2 to sugarSlide 56LE 10-18_1LE 10-18_2LE 10-18_3Concept 10.4: Alternative mechanisms of carbon fixation have evolved in hot, arid climatesPhotorespiration: An Evolutionary Relic?Slide 62C4 PlantsLE 10-19CAM PlantsLE 10-20The Importance of Photosynthesis: A ReviewLE 10-21Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPowerPoint Lectures for Biology, Seventh EditionNeil Campbell and Jane ReeceLectures by Chris RomeroChapter 10Chapter 10PhotosynthesisCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsOverview: The Process That Feeds the Biosphere•Photosynthesis is the process that converts solar energy into chemical energy•Directly or indirectly, photosynthesis nourishes almost the entire living worldCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Autotrophs sustain themselves without eating anything derived from other organisms•Autotrophs are the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules•Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules from water and carbon dioxideCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes•These organisms feed not only themselves but also the entire living worldLE 10-2LE 10-2PlantsUnicellular protistMulticellular algae CyanobacteriaPurple sulfurbacteria10 µm1.5 µm40 µmCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Heterotrophs obtain their organic material from other organisms•Heterotrophs are the consumers of the biosphere•Almost all heterotrophs, including humans, depend on photoautotrophs for food and oxygenCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 10.1: Photosynthesis converts light energy to the chemical energy of food•Chloroplasts are organelles that are responsible for feeding the vast majority of organisms•Chloroplasts are present in a variety of photosynthesizing organismsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsChloroplasts: The Sites of Photosynthesis in Plants•Leaves are the major locations of photosynthesis•Their green color is from chlorophyll, the green pigment within chloroplasts•Light energy absorbed by chlorophyll drives the synthesis of organic molecules in the chloroplast•Through microscopic pores called stomata, CO2 enters the leaf and O2 exitsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf•A typical mesophyll cell has 30-40 chloroplasts•The chlorophyll is in the membranes of thylakoids (connected sacs in the chloroplast); thylakoids may be stacked in columns called grana•Chloroplasts also contain stroma, a dense fluidLE 10-3LE 10-3Leaf cross sectionVeinMesophyllStomataCO2O2Mesophyll cellChloroplast5 µmOutermembraneIntermembranespaceInnermembraneThylakoidspaceThylakoidGranumStroma1 µmCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsTracking Atoms Through Photosynthesis: Scientific Inquiry•Photosynthesis can be summarized as the following equation:6 CO2 + 12 H2O + Light energy  C6H12O6 + 6 O2 + 6 H2 OCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Splitting of Water•Chloroplasts split water into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar moleculesLE 10-4LE 10-4Reactants:Products:6 CO212 H2OC6H12O66 H2O6 O2Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPhotosynthesis as a Redox Process•Photosynthesis is a redox process in which water is oxidized and carbon dioxide is reducedCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Two Stages of Photosynthesis: A Preview•Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part)•The light reactions (in the thylakoids) split water, release O2, produce ATP, and form NADPH•The Calvin cycle (in the stroma) forms sugar from CO2, using ATP and NADPH•The Calvin cycle begins with carbon fixation, incorporating CO2 into organic moleculesLE 10-5_1LE 10-5_1H2OLIGHTREACTIONSChloroplastLightLE 10-5_2LE 10-5_2H2OLIGHTREACTIONSChloroplastLightATPNADPHO2LE 10-5_3LE 10-5_3H2OLIGHTREACTIONSChloroplastLightATPNADPHO2NADP+CO2ADPP+iCALVINCYCLE[CH2O](sugar)Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 10.2: The light reactions convert solar energy to the chemical energy of ATP and NADPH•Chloroplasts are solar-powered chemical factories•Their thylakoids transform light energy into the chemical energy of ATP and NADPHCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Nature of Sunlight•Light is a form of electromagnetic energy, also called electromagnetic radiation•Like other electromagnetic energy, light travels in rhythmic waves•Wavelength = distance between crests of waves•Wavelength determines the type of electromagnetic energy•Light also behaves as though it consists of discrete particles, called photonsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•The