Photosynthesis, light dependent and light independent

Without ATP, life may not have existed, because it serves a critical role in providing the right amount of energy for thousands of chemical reactions to occur.

1. Photosynthesis General Biology 1 Lectures by Michael U. Batungbakal

2. Objectives Identify the end products of Light Dependent Reaction of Photosynthesis. Explain the importance of the end products of Light Dependent Reaction of Photosynthesis to the Calvin Cycle.

3. Objectives Iden tify the sub-stages of Calvin Cycle as well as the notable events that take . Enumerate the raw materials/ reactions and end products of Calvin Cycle.

4. Pigment molecules Light P680 e – Primary acceptor 2 1 e – e – 2 H + O 2 + 3 H 2 O 1 / 2 4 Pq Pc Cytochrome complex Electron transport chain 5 ATP Photosystem I (PS I ) Light Primary acceptor e – P700 6 Fd Electron transport chain NADP + reductase NADP + + H + NADPH 8 7 e – e – 6 Photosystem II (PS II )

5. Fig. 10-17 Light Fd Cytochrome complex ADP + i H + ATP P ATP synthase To Calvin Cycle STROMA (low H + concentration) Thylakoid membrane THYLAKOID SPACE (high H + concentration) STROMA (low H + concentration) Photosystem II Photosystem I 4 H + 4 H + Pq Pc Light NADP + reductase NADP + + H + NADPH +2 H + H 2 O O 2 e – e – 1 / 2 1 2 3 http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120072/bio13.swf::Photosynthetic%20Electron%20Transport%20and%20ATP%20Synthesis

6. ATP Photosystem II Photosystem I Primary acceptor Pq Cytochrome complex Fd Pc Primary acceptor Fd NADP + reductase NADPH NADP + + H + Cyclic electron flow uses only photosystem I and produces ATP, but not NADPH Cyclic electron flow generates surplus ATP, satisfying the higher demand in the Calvin cycle Some organisms such as purple sulfur bacteria have PS I but not PS II Cyclic electron flow is thought to have evolved before linear electron flow

7. Ribulose bisphosphate (RuBP) 3-Phosphoglycerate Short-lived intermediate Phase 1: Carbon fixation (Entering one at a time) Rubisco Input CO 2 P 3 6 3 3 P P P P ATP 6 6 ADP P P 6 1,3-Bisphosphoglycerate 6 P P 6 6 6 NADP + NADPH i Phase 2: Reduction Glyceraldehyde-3-phosphate (G3P) 1 P Output G3P (a sugar) Glucose and other organic compounds Calvin Cycle 3 3 ADP ATP 5 P Phase 3: Regeneration of the CO 2 acceptor (RuBP) G3P Carbon enters the cycle as CO 2 and leaves as a sugar named glyceraldehyde-3-phospate (G3P) For net synthesis of 1 G3P, the cycle must take place three times , fixing 3 molecules of CO 2 The Calvin cycle has three phases The Calvin cycle, like the citric acid cycle, regenerates its starting material after molecules enter and leave the cycle The cycle builds sugar from smaller molecules by using ATP and the reducing power of electrons carried by NADPH http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter39/calvin_cycle.html http://www.science.smith.edu/departments/Biology/Bio231/calvin.html

8. How do plants help the environment and humans?

9. How can you help th e plants to protect our environment?