8-3 The Reactions of Photosynthesis Photo Credit: ©Stone Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Inside a Chloroplast Photosynthesis takes place inside chloroplasts. Plant Chloroplast Plant cells Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Chloroplasts contain thylakoid membranes. Single thylakoid Chloroplast Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Grana are stacks of thylakoids. Granum Chloroplast Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Photosystems are the light-collecting units of the chloroplast. Contain chlorophyll. Photosystems Chloroplast Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Inside a Chloroplast Phases of Photosynthesis: Light reaction Dark reaction (Calvin cycle) 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 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Light Reaction Light Reactions: Chlorophyll absorbs light (energized) ATP is produced Water is split into Hydrogen & Oxygen Oxygen is released into the atmosphere NADPH transports Hydrogen atoms Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle Calvin Cycle: NADPH + ATP + CO2 produce 2 molecules of PGAL 2 PGAL’s form one glucose molecule Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle Six carbon dioxide molecules enter the cycle from the atmosphere and combine with six 5-carbon molecules. CO2 Enters the Cycle The Calvin cycle uses ATP and NADPH to produce high-energy sugars. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle The result is twelve 3-carbon molecules, which are then converted into higher-energy forms. The Calvin cycle uses ATP and NADPH to produce high-energy sugars. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle The energy for this conversion comes from ATP and high-energy electrons from NADPH. Energy Input 12 12 ADP 12 NADPH The Calvin cycle uses ATP and NADPH to produce high-energy sugars. 12 NADP+ Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Calvin Cycle Two of twelve 3-carbon molecules are removed from the cycle. Energy Input 12 12 ADP 12 NADPH The Calvin cycle uses ATP and NADPH to produce high-energy sugars. 12 NADP+ Copyright Pearson Prentice Hall

6-Carbon sugar produced Sugars and other compounds The Calvin Cycle The molecules are used to produce sugars, lipids, amino acids and other compounds. 12 12 ADP 12 NADPH The Calvin cycle uses ATP and NADPH to produce high-energy sugars. 12 NADP+ 6-Carbon sugar produced Sugars and other compounds Copyright Pearson Prentice Hall

5-Carbon Molecules Regenerated Sugars and other compounds The Calvin Cycle The 10 remaining 3-carbon molecules are converted back into six 5-carbon molecules, which are used to begin the next 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 Factors Affecting Photosynthesis Many factors affect the rate of photosynthesis, including: Water & Carbon Dioxide Temperature & pH Intensity of light Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 8-3 In plants, photosynthesis takes place inside the thylakoids. chloroplasts. photosystems. chlorophyll. 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