Ch10.pdf BIOLOGY 108 - 0001
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This 7 page Class Notes was uploaded by Koral Shah on Friday October 2, 2015. The Class Notes belongs to BIOLOGY 108 - 0001 at University of Missouri - Kansas City taught by Marilyn Yoder in Fall 2015. Since its upload, it has received 53 views. For similar materials see General Biology I in Biology at University of Missouri - Kansas City.
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Date Created: 10/02/15
Chapter 10 Photosynthesis 101 Conversion of Energy Photosynthesis plants39 chloroplasts capture light energy from the sun and convert it to energy leaves are the main point of photosynthesis in plants Mesophyll tissue in interior of the leaf Where most chloroplasts are found 3040 Chloroplasts per Mesophyll Cell Chloroplast Structure Stomata pores in leaves through Which C02 enters and Oxygen exits Stroma intermembrane uid in chloroplast Thylakoids membranous sacs in addition to double membrane of chloroplasts Granum a singular stack of thylakoid sacs Chlorophyll green pigment that gives leaves their color and absorbs light energy resides in Thylakoids Plant Cell Chloroplast Structure Inner Membrane I Stroma Figure 1 Granum Stack of Thylakolds 6 C02 12 H20 Light Energy gt C6H1206 6 02 6 H20 Disclaimer C6H1206 glucose is not ACTUALLY a product of photosynthesis it39s actually a 3 Carbon sugar that can be used to make glucose Reverse of Cellular Respiration Reactants 6 CO2 Products Cellular Respiration Photosynthesis Electrons transfer from sugar to oxygen Water is split into Hydrogen and Oxygen Forms water as a byproduct Electrons transfer from the water39s hydrogen to Electrons lose potential energy as they fall C02 down Electron Transport Chain Forms 02 as a byproduct Mitochondrion harnesses that energy to C02 is reduced to sugar synthesize ATP Electrons increase as moved from water to sugar requires energy endergonic Light produces required energy Light Reactions Calvin Cycle photo of photosynthesis synthesis of photosynthesis 1 Water is split hydrogen used as electron 1 Carbon Fixation occurs source 2 Fixed carbon is reduced to carbohydrate 2 Chlorophyll absorbs light energy to drive by NADPH used from light reactions transfer of electrons quotupquot chain 3 Energy required to convert C02 is 3 Electrons driven from H20 to NADP provided by ATP from light reactions acceptor 4 AND WE HAVE SUGAR NADP is NAD with phosphate group Occurs in Stroma 4 NADP is reduced to NADPH Light not directly needed 5 ATP is generated through Products from light reactions are required photophosphorylation NADPH and ATP Occurs in Thylakoids Light Required Final Electron Acceptor NADP Photophosphorylation addition of a phosphate group to ADP generates ATP NO SUGAR PRODUCED IN LIGHT REACTIONS Carbon Fixation carbon is incorporated into organic compounds in chloroplast Q 39 nght Reacuons RUBP EPhosphoglycerat 39I 1 I Photosystem ll Calvin ll 39 In Electron transport chain Cycle I Photosysteml l39 l Electron transport chal A Mg I i39ll a quot 639 Starch 7 339 Chloroplast Sucrose export 102 Light Reactions Properties of Light Wavelength length between crests of electromagnetic waves Light can exhibit both wave and particle properties Light as a Wave THE ELECTRO MAGNETIC SPECTRUM Wavelength metres Radio Microwave Infrared Visible Ultraviolet XRay Gamma Ray 1 l l l l l l l l l l l I l 103 1039 105 106 108 1039 1039quot2 WVWWWWW Frequency Hz H 104 108 10392 l 1015 10quot 10398 1020 Light as a particle Photons Shorter Wavelength Higher Photon Energy Longer Wavelength Lower Photon Energy Pigment substances that absorb visible light We see green leaves because chlorophyll absorbs blue and red light transmitting green back Spectrophotometer measures ability of a pigment to absorb various colors of light Absorption Spectrum graph plotting pigment39s light absorption versus wavelength Action Spectrum profiles relative effectiveness of different wavelengths plots different wavelengths against measure of photosynthetic rate what will make photosynthesis most effective violetblue and red least green Three Plant Pigments Chlorophyll a bluegreen and participates directly in light reactions Chlorophyll b olive green accessory pigment Carotenoids group of yellow and orange accessory pigments broaden spectrum of colors that can drive photosynthesis Photoprotection absorb and dissipate excessive light that would damage plants also present in human eyes ReactionCenter Complex organized association of proteins holding a special pair of chlorophyll LightHarvesting Complex includes many pigment molecules bound to proteins act as an antenna to the reactioncenter complex A Thylakoid membrane LT Lightharvesting Reaction Photo system STROMA A I L complexes center Pr39mary e39ec on 7 acceptor I L Pigment molecules Special chlorophyll 9 molecules Transfer of energy THYLAKOID SPACE 1 Pigment absorbs a photon light 2 Energy does the quotwavequot transferred from photon to photon until it gets to the reactioncenter complex 3 Chlorophyll a molecules39s electrons get excited to a higher orbital from the energy 4 Chlorophyll a39s excited electrons are passed off to the Primary Electron Acceptor redox reaction Two Photosystems in Thylakoids Photosystem II and Photosystem I PSII has P680 pigments best for absorbing 680nm wavelengths red PSI has P700 pigments best for absorbing 700nm wavelengths FAR red Linear Electron Flow OOOUlIgtUJIP 9 Photon strikes pigments in light harvesting complex of PSII Electrons are boosted to higher energy level as it falls the pigment next to it is boosted and so on Process continues until it reaches P680 pair of chlorophyll The excited electrons of P680 pair is transferred to primary electron acceptor Water is split giving its electrons to the P680 replaces ones taken by Primary Electron Acceptor H from water is released into thylakoid and O combines with another 0 to make 02 These electrons quotfallquot along the chain providing energy for synthesis of ATP P700 electrons become excited and are transferred to the PSI primary acceptor allowing P700 to accept electron from the chain from PSII From PSI39s primary acceptor electrons are transported on another chain which cadalyzes NADP reductase 10 NADP and H are added creating NADPH Ultimate Products ATP and NADPH complex 0Light b Pigment molecules Photosystem I PS I Photosystem 11 PS 11 Fv ds E39m Jun 393 Cyclic Electron Flow alternate path to linear ow uses PSI but not PSII only generates APT not NADPH 103 The Calvin Cycle Anabolic Cycle builds carbs from smaller molecules consuming energy C02 enters the cycle and leaves as Sugar Glyceraldehyde 3Phosphate G3P Net synthesis of one G3P requires 3 time through the cycle Phase 1 Carbon Fixation Rubisco enzyme that catalyzes the binding of C02 to a five carbon sugar Binding of C02 to 5 Carbon Sugar RuBP creates 6 Carbon Intermediate Sugar 6 Carbon Intermediate Sugar splits into two 3phosphoglycerate molecules Phase 2 Reduction Each 3phosphoglycerate molecule receives a phosphate group from ATP Electrons from NADPH reduces the molecules Each molecule loses a phosphate group gt G3P For every 3 molecules of C02 that enter the cycle 6 molecules of G3P are formed 0nly one molecule of G3P leaves the cycle to be used by the plant others are recycled to regenerate RuBP Phase 3 Regeneration of RuBP Remaining five molecules of G3P are rearranged into three molecules of RuBP This takes three ATP to accomplish RuBP can now receive C02 once again cycle starts over Net synthesis of one G3P molecule requires nine ATP39s and six NADPH39s from light reactions Input 30 Entering one co at a time 2 Phase 1 Carbon xation 0 5900000 mwu I V Shortlived intermediate 3900000 6000 Ribulosc bisphosphatc 3Phosphoglycerate Kt RuBP V 53975 I x gt 6 ADP 39 39 I iv L 3 ADP lt 7 J CALVIN 7 CYCLE 3Jiir s j u e pig lt3 cgtap at v 13Bisphosphoglycerate is s NADPH39 Phase 3 a Regeneration of 3 N b 6 NADP the CO acceptor 3922 39 gt 64 aqu p 5 G O O quotx L 6 O O O p quot Gcheraldehydeaphosphate phase 2 39 G39 Reduction r l l 1000 1 53quot Glucose and a sugar other organic Output compounds 104 Alternative Carbon Fixation C3 Plants fixation of carbon in Calvin cycle Via rubisco most plants forms a 3carbon compound in first steps of Calvin Cycle Photorespiration when plants close their stomata to conserve water and C02 intake goes down therefore the Calvin cycle is starved and rubisco binds to 02 instead of C02 producing a 2carbon sugar instead of 3carbon mitochondria and peroxisomes rearrange new compound and release C02 generates no ATP and no sugar THIS IS BAD Upside to Photorespiration neutralizes harmful elements of light C4 Plants forms a 4carbon compound in first steps of Calvin Cycle BundleSheath Cells tightly packed sheaths of cells around veins of the leaf between the sheaths and leaf surface are loosely arranged mesophyll cells C4 Pathway 1 PEP Carboxylase enzyme adds C02 to phosphoenolpyruvate PEP forming 4carbon product fixing the carbon 2 Mesophyll cells export 4carbon sugar products to bundleshealth cells through plasmodesmata 3 4carbon compound releases C02 regenerating pyruvate and transports to mesophyll cells 4 ATP from cyclic electron ow converts pyruvate to PEP continuing the cycle Advantageous for plants in hot and dry environments Figure 1017 C4 anatomy and pathway MESOPHYLL Mesophyll cell CELL C02 Bundle 3935 sheath cellquotquot39IV 39 itVA o l 39ctarb AIR Vein 39 7 Aw 8 0809 a e 39 SPACE vasculartissue Stoma 11 12f 39 77 I BUNDLE SHEATH CELL a C4 leaf anatomy if VASCULAR TISSUE b The C4 pathway Capyrlght 39l l quot N 39 3 Incquot EIOLOGVFouth Eamon Crassulacean Acid Metabolism CAM Plants Close stomata during the day keeping water in and open it at night taking in C02 Example Pineapple water storing plants Light reactions Calvin cycle lt i V 139 11quoti l L 39l Amino acids hl I t C map as Fatty acids Light reactions Calvin cycle reactions Are carried out by molecules in the Take place In the stroma thylakoid membranes Use An and App to Convert light energy to the chemical convert C02 to the energy of ATP and NADPH sugar GaP Split H20 and release 02 to the 0 Return ADP inorganic phosphate and NADPquot atmosphere to the light reactions Some random points to know Citric Acid Cycle releases 4 C0239s 2 per pyruvate
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