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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 8 Photosynthesis: Capturing Energy
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Light Composed of photons Visible light small portion of electromagnetic spectrum All energy travels as waves Shorter wavelengths have more energy than longer wavelengths
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Electromagnetic spectrum
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Chloroplasts Organelles enclosed by a double membrane Site of photosynthesis Located mainly within mesophyll cells inside leaf
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Site of photosynthesis
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Chlorophyll Main photosynthetic pigment Chlorophyll a, chlorophyll b, carotenoids, and other photosynthetic pigments are components of thylakoid membranes of chloroplasts
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Photosynthesis is redox process Light energy captured and converted to carbohydrates Hydrogens from water reduce carbon Oxygen derived from water becomes oxidized
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Two phases of photosynthesis Light-dependent –In thylakoids –Electrons energized by light generate ATP and NADPH Carbon fixation –In stroma –Compounds generated in phase one provide energy for formation of carbohydrate
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Overview of photosynthesis
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Photosystems I and II Two types of photosynthetic units involved in photosynthesis Each photosystem includes –Chlorophyll molecules –Multiple antenna complexes Photosystem I reaction center –P700 has absorption peak at 700 nm Photosystem II reaction center –P680 has absorption peak at 680 nm
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Photosystem
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Noncyclic electron transport ATP and NADPH formed Electrons energized by absorption of light and pass through electron transport chain to NADP + Series of redox reactions Electrons given up by P680 are replaced by electrons from photolysis of H 2 O
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Noncyclic electron transport
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Cyclic electron transport Electrons from photosystem I returned to photosystem I ATP produced by chemiosmosis No NADPH or O 2 generated
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy ATP synthesis and electron transport Electrons move down electron transport chain Protons (H + ) move from stroma to thylakoid lumen, creating proton gradient Greater concentration of H + lowers the pH
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Accumulation of protons in thylakoid lumen
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Electron transport and chemiosmosis
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Carbon fixation Energy of ATP and NADPH used in formation of organic molecules from CO 2 12 NADPH + 18 ATP + 6 CO 2 → C 6 H 12 O 6 + 12 NADP + + 18 ADP + 18 Pi + 6 H 2 O
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Three phases of Calvin cycle CO 2 uptake Carbon reduction RuBP regeneration
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Calvin cycle
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Summary of photosynthesis
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy C 3 and C 4 plant structure compared
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Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 8 Photosynthesis: Capturing Energy Summary of the C 4 pathway
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