8-3 The Reactions of Photosynthesis The reactants are: H2O (water) CO2 (carbon Dioxide) The Products are: O2 (Oxygen) C6H12O6 (CH2O in the picture is a sugar building block for glucose) Photo Credit: ©Stone Should we sing the song again? Or rap photosynthesis? Or Linkin Park? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Inside a Chloroplast In plants, photosynthesis takes place inside chloroplasts. Plant Chloroplast Plant cells Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Chloroplasts contain thylakoids—saclike photosynthetic membranes. Single thylakoid Chloroplast Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Thylakoids are arranged in stacks known as grana. A singular stack is called a granum. Granum Chloroplast Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters called photosystems, which are the light-collecting units of the chloroplast. Photosystems Chloroplast Copyright Pearson Prentice Hall

Light- dependent reactions Inside a Chloroplast H2O CO2 Light NADP+ ADP + P Light- dependent reactions Calvin Cycle Calvin cycle The process of photosynthesis includes the light-dependent reactions as well as the Calvin cycle. Chloroplast O2 Sugars Or rap photosynthesis? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Carriers Electron Carriers When electrons in chlorophyll absorb sunlight, the electrons gain a great deal of energy. Cells use electron carriers to transport these high-energy electrons from chlorophyll to other molecules. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Carriers One electron carrier molecule is NADP+. It transports electrons: NADP+ accepts and holds 2 high-energy electrons along with a hydrogen ion (H+) This converts the NADP+ into NADPH. Copyright Pearson Prentice Hall

Light-Dependent Reactions produce O2, oxygen gas convert ADP into ATP and NADP+ into NADPH. Video animation inside cell membrane. Copyright Pearson Prentice Hall

Light-Dependent Reactions Because of this system, light-dependent electron transport produces not only high-energy electrons but ATP as well. ATP synthase + O2 2H2O The light-dependent reactions use energy from sunlight to produce ATP, NADPH, and oxygen. ADP 2 NADP+ 2 2 NADPH Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle What is the Calvin cycle? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle The Calvin cycle uses ATP and NADPH from the light-dependent reactions and produces high-energy sugars (glucose). Because the Calvin cycle does not require light, these reactions are also called the light-independent reactions. Photosynthesis-Calvin Cycle and Cyclic Electron Flow Song Copyright Pearson Prentice Hall

5-Carbon Molecules Regenerated Sugars and other compounds The Calvin Cycle Reactants and Products of the Light Independent Reactions (Calvin Cycle). 12 12 ADP 6 ADP 12 NADPH 6 The Calvin cycle uses ATP and NADPH to produce high-energy sugars. 12 NADP+ 5-Carbon Molecules Regenerated Sugars and other compounds Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle The two sets of photosynthetic reactions work together. The light-dependent reactions trap sunlight energy in chemical form. The light-independent reactions use that chemical energy to produce stable, high-energy sugars from carbon dioxide and water. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 8-3 In plants, photosynthesis takes place inside the thylakoids. chloroplasts. photosystems. chlorophyll. Photosynthesis Rap (again): http://www.youtube.com/watch?v=pE82qtKSSH4&feature=related Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 8-3 Energy to make ATP in the chloroplast comes most directly from hydrogen ions flowing through an enzyme in the thylakoid membrane. transfer of a phosphate from ADP. electrons moving through the electron transport chain. electrons transferred directly from NADPH. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 8-3 NADPH is produced in light-dependent reactions and carries energy in the form of ATP. high-energy electrons. low-energy electrons. ADP. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 8-3 What is another name for the Calvin cycle? light-dependent reactions light-independent reactions electron transport chain photosynthesis Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 8-3 Which of the following factors does NOT directly affect photosynthesis? wind water supply temperature light intensity Copyright Pearson Prentice Hall

Organize the overall reaction + O2 C6H12O6 CO2 Photosynthesis H2O Products sunlight Reactants +

Organize the Light Reaction reaction + O2 sunlight ATP Reactants Thylakoid Membrane Light Reaction Products NADPH + H2O + H+ +