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Photosynthesis Processes. Overview Absorption of light energy – Sun hits chloroplasts Conversion to chemical energy – Light dependant reaction Storage.

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Presentation on theme: "Photosynthesis Processes. Overview Absorption of light energy – Sun hits chloroplasts Conversion to chemical energy – Light dependant reaction Storage."— Presentation transcript:

1 Photosynthesis Processes

2 Overview Absorption of light energy – Sun hits chloroplasts Conversion to chemical energy – Light dependant reaction Storage of energy in sugars – Light independent reaction Absorption of light energy – Sun hits chloroplasts Conversion to chemical energy – Light dependant reaction Storage of energy in sugars – Light independent reaction

3 2 Stages of Photosynthesis 1.Light Dependant Reaction Takes place in Grana (thylakoid membrane) Products – ATP, O₂, NADPH 2.Light Independent Reaction – Calvin Cycle Takes place in the stroma Products – Glucose, NADP⁺, ADP 1.Light Dependant Reaction Takes place in Grana (thylakoid membrane) Products – ATP, O₂, NADPH 2.Light Independent Reaction – Calvin Cycle Takes place in the stroma Products – Glucose, NADP⁺, ADP

4 Light Dependant Reaction Takes place in thylakloid membrane of the chloroplast

5 Light Dependant Reaction

6 1.Light strikes PSII – 2 electrons are excited – Simultaneously - H₂O split into to H⁺ and ½ O₂ (photolysis) 2.Electrons flow down ETC (electron transport chain) – Providing energy for production of ATP – Electrons enter photosystem I 3.Light strikes PSI – Exciting electrons 4.Electrons flow down to NADP⁺ electron acceptor – Provide energy for production of NADPH (used in light independent reactions) 1.Light strikes PSII – 2 electrons are excited – Simultaneously - H₂O split into to H⁺ and ½ O₂ (photolysis) 2.Electrons flow down ETC (electron transport chain) – Providing energy for production of ATP – Electrons enter photosystem I 3.Light strikes PSI – Exciting electrons 4.Electrons flow down to NADP⁺ electron acceptor – Provide energy for production of NADPH (used in light independent reactions)

7 Light Dependant Reaction

8 Light Independent Reactions Calvin Cycle No light required Carbohydrates are synthesized from CO₂ using the ATP and NPDH formed in light reactions No light required Carbohydrates are synthesized from CO₂ using the ATP and NPDH formed in light reactions

9 Calvin Cycle 4 Steps 1.Carbon Fixation 2.Energy conversion 3.Release one molecule of sugar G3P 4.Regeneration of RuBP 4 Steps 1.Carbon Fixation 2.Energy conversion 3.Release one molecule of sugar G3P 4.Regeneration of RuBP

10 Calvin Cycle Step 1 – Carbon Fixation – Three molecules of CO₂ combine with 5-C sugars RuBP (Ribulose biphosphate) Enzyme is Rubisco – Each CO₂ forms a 6-C molecule which splits into two 3-C acids (PGA) Step 1 – Carbon Fixation – Three molecules of CO₂ combine with 5-C sugars RuBP (Ribulose biphosphate) Enzyme is Rubisco – Each CO₂ forms a 6-C molecule which splits into two 3-C acids (PGA)

11 Calvin Cycle Step 2 – Energy Conversion – 2 chemical reactions Use 6 molecules of ATP ATP ADP + P And Use 6 molecules of NAPDH NADPH NADP⁺ – Producing 6 molecules of 3-C sugar G3P (phosphoglyeralehyde) Step 2 – Energy Conversion – 2 chemical reactions Use 6 molecules of ATP ATP ADP + P And Use 6 molecules of NAPDH NADPH NADP⁺ – Producing 6 molecules of 3-C sugar G3P (phosphoglyeralehyde)

12 Calvin Cycle Step 3 – Release one molecule of G3P – Five of the G3P molecules remain in the cycle – One G3P molecule in released as a product Step 3 – Release one molecule of G3P – Five of the G3P molecules remain in the cycle – One G3P molecule in released as a product

13 Calvin Cycle Step 4 – Regeneration of RuBP – Series of chemical reactions Use 3 ATP to convert 5 G3P molecules into 3 RuBP molecules Step 4 – Regeneration of RuBP – Series of chemical reactions Use 3 ATP to convert 5 G3P molecules into 3 RuBP molecules

14 Calvin Cycle Takes two molecules of G3P to produce one molecule of glucose – So 6 molecules of CO₂ 18 molecules of ATP 12 molecules of NADPH Takes two molecules of G3P to produce one molecule of glucose – So 6 molecules of CO₂ 18 molecules of ATP 12 molecules of NADPH

15 Photosynthesis Recap


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