UT Knoxville BIOL 140 - Chapter 10 (41 pages)

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Chapter 10 Photosynthesis 2011 Pearson Education Inc An Overview of Photosynthesis Photosynthesis is the process of using sunlight to produce carbohydrate This process requires sunlight carbon dioxide and water and produces oxygen as a by product The overall reaction when glucose is the carbohydrate can be written as 6 CO2 12 H2O light energy C6H12O6 6 O2 6 H2O Photosynthesis contrasts with cellular respiration Photosynthesis is endergonic Reduces CO2 to sugar Cellular respiration is exergonic Oxidizes sugar to CO2 2011 Pearson Education Inc Photosynthesis Two Linked Sets of Reactions Photosynthesis consists of two linked sets of reactions lightdependent reactions produce O2 from H2O and Calvin cycle reactions produce sugar from CO2 The reactions are linked by electrons which are released in the light dependent reactions when water is split to form oxygen gas and then transferred to the electron carrier NADP forming NADPH The Calvin cycle then uses these electrons and the potential energy in ATP to reduce CO2 to make sugars 2011 Pearson Education Inc 2011 Pearson Education Inc The Structure of the Chloroplast Photosynthesis occurs in the chloroplasts of green plants algae and other photosynthetic organisms Chloroplasts are surrounded by two membranes The internal membranes of chloroplasts form flattened vesicle like structures called thylakoids some of which form stacks called grana Thylakoid membranes contain large quantities of pigments The most common pigment is chlorophyll The fluid filled space between the thylakoids and the inner membrane is the stroma 2011 Pearson Education Inc 2011 Pearson Education Inc The Nature of Light Energy Electromagnetic radiation is a form of energy Light is a type of energy electromagnetic radiation that acts both particle like and wave like As a particle light exists in discrete packets called photons As a wave light can be characterized by its wavelength the distance between two successive wave crests 2011 Pearson Education Inc