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Photosynthesis and Cellular Respiration

Photosynthesis and Cellular Respiration. Photosynthesis occurs in the chloroplasts , a double membrane organelle. The inner space of the thylakoid is simply called the thylakoid space , and thylakoids themselves are found in stacks called grana.

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Photosynthesis and Cellular Respiration

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  1. Photosynthesis and Cellular Respiration

  2. Photosynthesis occurs in the chloroplasts, a double membrane organelle. The inner space of the thylakoid is simply called the thylakoid space, and thylakoids themselves are found in stacks called grana. The membranes of the thylakoids are filled with chlorophyll - gives plants their green color. The inner fluid of the chloroplast is the stroma. Inside the stroma are flattened membrane structures called thylakoids.

  3. Basic Reactions • Light-dependent reactions • Requires light • Purpose: Convert solar energy into ATP and a reduced electron carrier NADPH • Occurs in the thylakoid • Light-independent reactions (Calvin Cycle) • Occurs in the stroma of chloroplast • Relies on the energy (ATP and NADPH) from the light-dependent reactions • Produces a three-carbon carbohydrate called glyceraldehyde3-phosphate (G3P) - used to form glucose and other carbohydrates

  4. Two kinds of Light Dependent Reactions: Linear Electron Flow and Cyclic Electron Flow • Thylakoid membrane is studded with complexes of proteins and light-absorbing pigments • Called photosystems, 2 types: • Photosystem I: reaction center called p700 (absorbs 700nm light) • Photosystem II: reaction center called p680 (absorbs 680nm light) • Complexes can work together in Linear Electron Flow or • Photosystem I can work alone performing Cyclic Electron Flow

  5. Linear Electron Flow Step 5: The H+ create a chemiosmotic gradient that synthesizes ATP as the H+ are moved through a membrane protein called ATP synthase. Step 4: The excited e- from PS I pass along membrane proteins to NADP+, which is reduced to NADPH in the stroma. Step 2: Energized e- pass along membrane proteins, some of e- energy is used to pump H+ into the lumen Step 3: The e- goes to PS I replacing e- that PS I lost when hit by light • Step 1: Light hits PS II, which excites some of chlorophyll A’s e-. H2O supplies e-, creating O2 and H+ in the lumen

  6. Cyclic Electron Flow Step 2: Electron travels through the electron transport system proteins, pumping hydrogen ions into the lumen Step 3: Electron returns to PSI chemiosmotic gradient is used to make ATP Step 1: Light energy energizes electrons from PSI

  7. Light-Independent Reactions (Calvin Cycle) – (C3 carbon fixation) (Citric Acid Cycle) RuBP CO2 • C3 Pathway - G3P, a three-carbon molecule is the first stable product • CO2 combines with a 5-carbon molecule called RuBP to make an unstable six-carbon compound. • The enzyme RuBisCo, catalyzes this reaction. • Summary: • Step 1: 6 RuBP and 6 CO2 at start. • Step 2: 12 ATP and 12 NADPH convert 12 3-PG (the product of RuBP and Co2) into 12 G3P, an energy-rich molecule. • Step 3: ADP and NADP+ are released and then recycled into the thylakoid where they will again be available for the light-dependent reactions. • Step 4: 2 of the G3P are used to make glucose while the remaining 10 are rearranged into 6 RuBPs ready for the next round of the cycle. 3-PG 3-PG G3P 1,3-BPG

  8. Photorespiration, C4 Pathway, and CAM Photosynthesis • Photorespiration: O2 instead of CO2 is added to RuBP. Reduces efficiency of photosynthesis. • C4 carbon fixation: 4-carbon molecule is first product. CO2 is fixed by PEP carboxylase in mesophyll cells and shuttled by bundle sheath cells surrounding vascular tissue. Remove CO2 so molecule can enter Calvin Cycle. ATP recycles PEP. Developed after C3. • CAM Photosynthesis: Arid conditions, absorb Co2 at night to make 4-carbon acid malate, then used during photosynthesis during the day.

  9. Cellular Respiration • Breakdown of molecules to gain energy (ATP) • Two types: • Anaerobic: no O2,in cytoplasm • Aerobic: O2, in cytoplasm then mitochondria

  10. Anaerobic Respiration • Net production of 2 ATP • Glycolysis: splitting of glucose, breaks into 2 pyruvic acid molecules • Fermentation: pyruvic acid is converted to either lactic acid or ethanol and CO2

  11. Anaerobic respiration • Glycolysis produces: • 2 ATP • 2 NADH • 2 pyruvate • Pyruvate is reduced by NADH (becoming NAD+) producing either: • Ethanol (yeast) • Lactic Acid (muscle cells)

  12. Aerobic respiration • Glycolysis: splitting of glucose, breaks into 2 pyruvic acid molecules • Pyruvate Dehydrogenase Complex (PDC): Group of enzymes that prepare pyruvate to enter Kreb’s Cycle • Kreb’s Cycle: Acetyl Co-A is combined with oxaloacetic acid, broken down 1 carbon at a time. Runs twice for each glucose molecule, 3 NADH, 1 FADH2, and 1 ATP made. • Electron Transport and Oxidative Phosphorylation: Return electron carriers to empty state, use energy from electrons to make ATP

  13. Electron transport occurs on inner membrane. Glycolysis occurs in cytoplasm PDC and Kreb’s Cycle occur in matrix.

  14. Glycolysis • http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html Link is already open on computer, click F3 to minimize window and view.

  15. Formation of acetyl coA • Pyruvate formed from Glycolysis has 3 carbon atoms • The Kreb’s Cycle can only accept a molecule with 2 carbon atoms. • PDC removes 1 of the carbons and attaches the remaining 2 carbon molecule to coenzyme A • Products (per glucose molecule = 2 pyruvate): • 2 acetyl Co-A • 2 NADH • 2 CO2

  16. Krebs Cycle Link is already open on computer, click F3 to minimize window and view. • http://www.youtube.com/watch?v=-cDFYXc9Wko#t=00m34s 3 NADH, 1 FADH2, and 1 ATP made

  17. Oxidative phosphorylation (Electron Transport Chain) • NADH and FADH2 pass e- to carrier molecules, e- passed until given to oxygen, forming H2O • Oxygen is final electron acceptor • e-carriers pump H+ ions into intermembrane, creating gradient of H+ ions • H+ ions cross by help from ATP Synthase, a phosphate is added to ADP, creating ATP

  18. Works Cited • http://micro.magnet.fsu.edu/cells/chloroplasts/images/chloroplastsfigure1.jpg • http://commons.wikipedia.org/wiki/File:Thylakoid_membrane.png • http://www.sivabio.50webs.com/plas015.jpg • P. Roisen Notes • http://images.search.yahoo.com/r/_ylt=A2KJkIbilZlP2zYA8FijzbkF;_ylu=X3oDMTBpcGszamw0BHNlYwNmcC1pbWcEc2xrA2ltZw--/SIG=13p4uluto/EXP=1335494242/**http%3a//www.syngenta.com/country/uk/en/learning-zone/KS345/biology/Pages/Photosynthesis_in_Action.aspx • http://upload.wikimedia.org/wikipedia/commons/8/8e/Calvin-cycle4.svg • http://micro.magnet.fsu.edu/cells/mitochondria/mitochondria.html • https://wikispaces.psu.edu/download/attachments/40045009/Krebs_cycle.jpg • http://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Mitochondrial_electron_transport_chain.png/778px-Mitochondrial_electron_transport_chain.png

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