Chapter 10 Photosynthesis 1 of the suns energy is absorbed by plants Primary producers o Photosynthetic autotrophs o Chemosynthetic autotrophs Some bacteria deep ocean o Light Excitation Chlorophyll Electromagnetic radiation in a specific band of wavelength ROYGBIV Visible Spectrum long wavelength high heat low energy short wavelength low heat high energy o Ground state excited state donate electrons for cytochromes o Designed for light excitation o Several different kinds o Chlorophyll A is most common most important o Consists of magnesium porphyrol ring long tail o Photosynthesis depends entirely on light in the visible portion of the spectrum o Chlorophyll absorbs primarily in B V R regions of the spectrum Chloroplasts o Carortenoids O Y pigments o Phycobilins O Y pigments o Thykaloid flattened sacs o Stroma outside of the thykaloids o Grana stacks of thykaloids Chemistry of Photosynthesis Absorb more in green yellow spectrum o Classic experiment o Labeled H2O with O18 heavy water H2 18 O 18 O2 o Labeled CO2 with 18 O C 18 O2 carbs Proves that O2 produced from plants comes from H2O o Simple C2 6CO2 Photosynthesis Photosystem I P700 Photosystem II P680 Light Dependent Reactions Peak of light absorption is at 700nm wavelength Peak of light absorption is at 680nm wavelength Non cyclic electron transport photophosphorylation Produces ATP NADPH O2 Photolytic dissociation of H2O Occurs in eukaryotes One way flow of electrons Energy used to pump protons from the stroma to thylakoid interior Plant in bright light pH 4 acidic Cyclic electron transport Bacteria and Prokaryotes Begins with P700 No O2 No NADPH ATP yes Light Independent Reactions Calvin cycle affects reaction converted 3 ATP to 3 ADP 3 5 carbon molecules RuBisCO 3 CO2 6 3 carbon molecules 6 ATP to 6 ADP 6 NADPH to 6 NADP 6 3 carbon molecules 5 3 carbon molecules glucose starch RuBisCO activity of this enzyme regulates the cycle C3 pathway Carbon dioxide fixation