Presentation is loading. Please wait.

Presentation is loading. Please wait.

THE CALVIN CYCLE: REDUCING CO 2 TO SUGAR © 2012 Pearson Education, Inc.

Similar presentations


Presentation on theme: "THE CALVIN CYCLE: REDUCING CO 2 TO SUGAR © 2012 Pearson Education, Inc."— Presentation transcript:

1 THE CALVIN CYCLE: REDUCING CO 2 TO SUGAR © 2012 Pearson Education, Inc.

2 7.10 The Calvin cycle generates sugar within chloroplast GOAL - Reduce CO 2 to produce the 3-Carbon sugar G3P. Reactants: CO 2 enter from stomata, ATP and NADPH from light reactions A plant cell may then use G3P to make glucose and other organic molecules. Equation for Calvin Cycle: 3 CO ATP + 6 NADPH G3P + 9 ADP + 6 NADP + + P © 2012 Pearson Education, Inc. Input Output: G3P Calvin Cycle CO 2 ATP NADPH

3 7.10 The Calvin Cycle The steps of the Calvin cycle include –carbon fixation, –reduction, –release of G3P, and –regeneration of the starting molecule ribulose bisphosphate (RuBP). © 2012 Pearson Education, Inc.

4 11 P P P PGA RuBP CO 2 Rubisco Input: Step Carbon fixation Calvin Cycle Rubisco = enzyme responsible for Carbon fixation: RuBP + CO PGA

5 Figure 7.10B_s P P P P P ATP ADP NADPH NADP G3P 3-PGA RuBP CO 2 Rubisco Input: Step Reduction Step Carbon fixation Calvin Cycle

6 Figure 7.10B_s Glucose and other compounds P P P P P P P ATP ADP NADPH NADP G3P 3-PGA RuBP CO 2 Rubisco Input: Output: Step Release of one molecule of G3P Step Reduction Step Carbon fixation Calvin Cycle

7 Figure 7.10B_s Glucose and other compounds P P P P P P P ATP ADP NADPH NADP G3P 3-PGA RuBP CO 2 Rubisco Input: Output: Step Regeneration of RuBP Step Release of one molecule of G3P Step Reduction Step Carbon fixation Calvin Cycle

8 CO 2 G3P 3-PGA RuBP Sugars Calvin Cycle (in stroma) Stroma Cellular respiration Other organic compounds Cellulose Starch The Fate of G3P 50% of carbs made by photosynthesis are used as fuel for plants –Cellular respiration in the mitochondria!!! G3P serves as starting material for making other organic molecules: –proteins, lipids, and cellulose. Excess carbs stored as starch in roots, stems, etc.

9 Photosynthesis and Cellular Respiration Form a Cycle!! © 2012 Pearson Education, Inc. sun ATP Photosynthesis (chloroplasts) Respiration (mitochondria) O2O2 glucose sugar CO 2 H2OH2O + + photoautotrophs Heterotrophs and autotrophs USED FOR CELLULAR WORK!! ATP produced by light reactions is ONLY used by Calvin cycle - never leaves chloroplast!

10 Factors Affecting the Rate of Photosynthesis

11 Photorespiration decreases energy yields in plants!! Under water stress or dehydration, –Stomata close due to decreased turgor pressure of guard cells –Gas exchange reduced -- O 2 levels increase, CO 2 levels decrease –Rubisco adds O 2 to RuBP instead of CO 2 –This process is called photorespiration because it occurs in the light, consumes O 2, releases CO 2, wastes ATP resources!!! © 2012 Pearson Education, Inc. Photorespiration = Reduced energy yields due to high O 2 levels!!

12 Typical Plants are C 3 Plants - Fix CO 2 by Rubisco forming 3-PGA C 3 plants are more affected by Photorespiration! 3-PGA

13 Fig. 6.15a

14 Alternative methods of Carbon Fixation to Prevent Photorespiration C 4 plants have evolved a means of –Limiting water loss while optimizing the Calvin cycle. C 4 plants first fix CO 2 into a four- carbon compound. © 2012 Pearson Education, Inc. Calvin Cycle Sugarcane Mesophyll cell Bundle- sheath cell CO 2 4-C compound CO 2 3-C sugar C 4 plant

15 Fig. 6.15a

16 Adaptations to Prevent Photorespiration, contd CAM plants conserve water by opening their stomata and admitting CO 2 only at night. CO 2 is fixed into a four- carbon compound, –which banks CO 2 at night and –releases it to the Calvin cycle during the day. © 2012 Pearson Education, Inc. Calvin Cycle Pineapple CO 2 3-C sugar CAM plant Day CO 2 4-C compound Night

17 You should now be able to 1.Define autotrophs, heterotrophs, producers, and photoautotrophs. 2.Describe the structure of chloroplasts and their location in a leaf. 3.Explain how plants produce oxygen. 4.Describe the role of redox reactions in photosynthesis and cellular respiration. 5.Compare the reactants and products of the light reactions and the Calvin cycle. © 2012 Pearson Education, Inc.

18 You should now be able to 6.Describe the properties and functions of the different photosynthetic pigments. 7.Explain how photosystems capture solar energy. 8.Explain how the electron transport chain and chemiosmosis generate ATP, NADPH, and oxygen in the light reactions. 9.Compare photophosphorylation and oxidative phosphorylation. 10.Describe the reactants and products of the Calvin cycle. © 2012 Pearson Education, Inc.

19 You should now be able to 11.Compare the mechanisms that C 3, C 4, and CAM plants use to obtain and use carbon dioxide. 12.Review the overall process of the light reactions and the Calvin cycle, noting the products, reactants, and locations of every major step. 13.Describe the greenhouse effect. 14.Explain how the ozone layer forms, how human activities have damaged it, and the consequences of the destruction of the ozone layer. © 2012 Pearson Education, Inc.


Download ppt "THE CALVIN CYCLE: REDUCING CO 2 TO SUGAR © 2012 Pearson Education, Inc."

Similar presentations


Ads by Google