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Catalyst Could humans survive without plants? Why, if at all, are plants important? Cell Parts: Chloroplast Photosynthesis: occurs only in plants (not animals!) 6CO2 + 6H2O (carbon dioxide) (water) absorb through leaves from roots + light (energy) C6H12O6 + (glucose sugar) from sun stored in plant; for plant use or animal use with cellular respiration Image Source: http://upload.wikimedia.org/wikipedia/commons/1/11/Chloroplast-new.jpg 6O2 (oxygen) released from leaves Chloroplast: capture light energy; make food energy Cell Parts: Chloroplast Thylakoid: flattened discs containing chlorophyll Granum (pl. Grana): stack of thylakoids Stroma: fluid inside chloroplast (similar to a cell’s cytoplasm) Lamella: links thylakoids in grana together Lumen: inside of the thylakoid Image Source: http://upload.wikimedia.org/wikipedia/commons/1/11/Chloroplast-new.jpg Cell Parts: Chloroplast Chlorophyll: pigment in chloroplasts that absorbs light Review:Visible Light Spectrum Violet Indigo Blue Green Yellow Orange Red “VIB G YOR” (or “ROY G BIV”) Cell Parts: Chloroplast The color you see is the color that is reflected Reflects: RED R O Y G Absorbs: OTHER COLORS B I V We See: RED Chlorophyll reflects green; absorbs ROYBIV! Light energy the plant uses!!!! Cell Parts: Chloroplast Phase I: Light-Dependent Reactions Phase 2: Light-Independent Reactions / Calvin Cycle Image Source: bioweb.uwlax.edu Cell Parts: Chloroplast Phase 1: Light-Dependent Reactions Occurs at thylakoid membrane (Lumen Stroma) Requires light (dependent) Cell Parts: Chloroplast Phase I: Light-Dependent Reactions Another e- carrier (like NAD+, FAD) STROMA Light H+ H+ NADP+ Light 4H+ NADPH e- ATP ADP P Photosystem II e- Thylakoid Membrane Ferrodoxin Photosystem I H+ H2 O e- 2H+ ½O 2 H+ H+ H+ H+ LUMEN ATP Synthase (enzyme/protein) Cell Parts: Chloroplast Phase 1: Light-Dependent Reactions Another e- carrier (like NAD+, FAD) Mini-Steps: 1. Photosystem II absorbs light energy to spilt STROMA water into: oxygen, H+s in lumen, & activated Light H H NADP+ + + Light 4 H + e- that enters the ETC. e - 2. Electron Transport Chain – e-s move through Photosystem II Photosystem I absorbs light energy and reenergizes e-, which moves to ferrodoxin ADP P membrane to pump H+s into lumen. 3. A TP NADPH e - Ferrodoxin Thylakoid Membrane Photosystem I (protein) to form NADPH. 4. H+s accumulate in lumen to create a gradient e + H + H + thylakoid membrane through ATP Synthase, ADP is converted into ATP. + H 2H ATP Synthesis – As H+s move across H + H2 O - (high [H+] in lumen, low [H+] in stroma). 5. H + ½ O2 Chemiosmosis LUMEN ATP Synthase (enzyme/protein) Cell Parts: Chloroplast Phase 2: Calvin Cycle / Light-Independent Reactions In stroma Doesn’t directly require light energy (independent) ATP & NADPH = energy, but not stable converted to glucose sugar. Cell Parts: Chloroplast Phase 2: Calvin Cycle 6 6 CO2 (3-phosphoglyceric acid) ribulose 1,5-bisphosphate C C C C C 12 3-PGA C C 6 ADP 6 ATP 6 Transported from chloroplast to make glucose, fructose, starch, etc. (carbohydrates / sugars) C C C C 12 ATP Calvin Cycle ribulose 5-phosphate 12 ADP C 12 NADPH Rubisco 2 12 NADP+ G3P 12 C C C C C G3P C C (glyceraldehyde 3-phosphate) Cell Parts: Chloroplast Phase 2: Calvin Cycle Mini-Steps: 1. 2. 3. 4. Carbon Fixation: Carbon dioxide joins a five-carbon molecule to make twice as many three-carbon molecules. ATP & NADPH turn 3-PGA into G3P (a high energy molecule). ATP supplies phosphate groups; NADPH supplies H+s and e-s. Two G3P molecules leave to make glucose & other carbohydrates. Rubisco (enzyme/protein) converts remaining ten G3P molecules into five-carbon molecules to be used in carbon fixation. 6 6 CO2 (3-phosphoglyceric acid) ribulose 1,5-bisphosphate C C C C C 12 3-PGA C C 6 ADP 6 ATP 6 C C C C 12 ATP Calvin Cycle ribulose 5-phosphate C 12 ADP C 12 NADPH Rubisco 2 12 NADP+ G3P 12 C C G3P (glyceraldehyde 3phosphate) C C C C Cell Parts: Chloroplast Phase I: Light-Dependent Reactions water: H+s, oxygen, & e-. Photosystem II uses light to split ETC: e- pumps H+s into lumen. Photosystem I re-energizes e- with light: forms NADPH. H+s in lumen create a concentration gradient. H+s move across thylakoid membrane through ATP Synthase: converts ADP into ATP Phase 2: Light-Independent Reactions / Calvin Cycle CO2 molecules join with 5-carbon molecules to make 3-PGA molecules. NADPH and ATP from Light-Dependent Reactions turn 3-PGA into G3P. Two G3P molecules leave the Calvin Cycle to form glucose & other carbohydrates. Remaining G3P molecules converted by Rubisco into 5-carbon molecules that restart the cycle. Image Source: bioweb.uwlax.edu