Chapter 8 Photosynthesis

8-3 The Reactions of Photosynthesis Inside the Chloroplast Thylakoids – Sac like membrane structures inside the chloroplasts Grana – Stacks of Thylakoid disks. Sites of the “Light Dependent Reaction” Stroma – Fluid filled space outside the Thylakoids Site of the “Light Independent Reaction” or “Calvin Cycle”

8-3 The Reactions of Photosynthesis

8-3 The Reactions of Photosynthesis NADPH Nicatinamide Adenine Dinucleotide Phosphate – “Carrier Molecule” Molecule – Transfers high energy electrons from the chlorophyll to other molecules. Carries Hydrogen Ions (H+) H NADP

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Requires light Occurs in the Thylakoids H2O is split O2 is given off as waste NADP picks up H+ and carries to the Calvin Cycle ADP picks up a Phosphate & converted to ATP, which is taken to the Calvin Cycle

Figure 8-7 Photosynthesis: An Overview Section 8-3 H2O O2 Sugars CO2 Light Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH Go to Section:

8-3 The Reactions of Photosynthesis Light-Dependent Reactions 3 step process Photosystem II Electron Transport Chain (ETC) Photosystem I

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Photosystem II (discovered 2nd) Light is absorbed by chlorophyll Water is split – O2 given off as waste

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Electron Transport Chain High Energy Electrons (H+) travel down the Electron Transport Chain (ETC) Provides energy for channel proteins to pump H+ inside the thylakoid membrane

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Photosystem I (discovered 1st) Chlorophyll absorbs more light energy which is used to convert NADP+ into NADPH (taken to Calvin Cycle) H+ inside the thylakoid pass through ATP synthase (channel protein) Energy is used to convert ADP into ATP (taken to Calvin Cycle)

Figure 8-10 Light-Dependent Reactions Section 8-3 Hydrogen Ion Movement Photosystem II Chloroplast ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma Electron Transport Chain Photosystem I ATP Formation Go to Section:

8-3 The Reactions of Photosynthesis Light Independent Reaction - “Calvin Cycle” CO2 enters the stroma NADPH drops off H+ NADP returns to thylakoid ATP provides energy to run Calvin Cycle ADP return to thylakoid CO2 and H combine to make sugar C6H12O6

Figure 8-7 Photosynthesis: An Overview Light H2O O2 Sugars CO2 Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH Go to Section:

8-3 The Reactions of Photosynthesis Light Independent Reaction - “Calvin Cycle” Steps CO2 enters the Calvin Cycle 6CO2 combine with six 5 carbon molecules to produce twelve three carbon molecules Energy Input – From ATP and NADPH One 6 Carbon sugar molecule produced Two 3 carbon molecules combine with H (from NADPH) to form one C6H12O6 5 Carbon molecules regenerated ten remain 3 carbon molecules are converted back into six 5 carbon molecules H2O is reformed and released through transpiration

Figure 8-11 Calvin Cycle Section 8-3 CO2 Enters the Cycle Energy Input ChloropIast 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced Sugars and other compounds Go to Section:

8-3 The Reactions of Photosynthesis Light Dependent Reaction Energy Light Reactants (What comes in) H2O NADP ADP Products (What goes out) O2 NADPH ATP Calvin Cycle Energy ATP NADPH Reactants (What comes in) CO2 Products (What goes out) C6H12O6 NADP ADP

8-3 The Reactions of Photosynthesis Factors Affecting Photosynthesis Availability of water Temperature Amount of light Intensity of light