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Photosynthesis and Respiration

Photosynthesis and Respiration. Energy and ATP. ATP Adenosine triphosphate Adenine, 5-carbon sugar, 3 phosphate groups ADP Adenosine diphosphate Adenine, 5-carbon sugar, 2 phosphate groups. ADP and ATP. Storing energy

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Photosynthesis and Respiration

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  1. Photosynthesis and Respiration

  2. Energy and ATP • ATP • Adenosine triphosphate • Adenine, 5-carbon sugar, 3 phosphate groups • ADP • Adenosine diphosphate • Adenine, 5-carbon sugar, 2 phosphate groups

  3. ADP and ATP • Storing energy • When a cell has energy available, it can store small amounts by adding a phosphate group to ADP, producing ATP • Releasing energy • Breaking bonds between the 2nd and 3rd phosphate groups • Powers several cellular activities • Active transport, protein synthesis, muscle contraction

  4. Photosynthesis • Method of converting sun energy into chemical energy usable by cells • Autotrophs utilize this process • Photoautotrophs- light • Chemoautotrophs- chemicals • Equation 6CO2 + 6H2O + light → C6H12O6 + 6O2

  5. Chloroplast

  6. Electron Carriers • Carrier molecule- a compound that can accept a pair of high-energy electrons and transfer them along with most of their energy to another molecule • Process: electron transport • Molecule: electron transport chain

  7. NADP+: NADP+ accepts and holds 2 high-energy electrons along with H+ • When this occurs it becomes NADPH • NADPH can then carry high-energy electrons to chemical reactions elsewhere

  8. Light-Dependent Reactions • Require light • Produce oxygen gas • Convert ADP and NADP into ATP and NADPH

  9. Light-Dependent Reactions • Pigments in photosystem II absorb light • Energy is absorbed by electrons which are passed on to electron transport chain • Electrons come from breaking bonds between water molecules • Create 2 electrons, H+ ions, and oxygen

  10. Light-Dependent Reactions 3. Electrons move through electron transport chain • from photosystem II to photosystem I • Energy is used to transport H+ ions from stroma to inner thylakoid 4. Pigments in photosystem I use energy from light to reenergize the electrons • NADP+ picks up high energy electrons and H+ ions • Becomes NADPH

  11. Light-Dependent Reactions 5. H+ ions are continuously pumped into thylakoid membrane • Inside= positively charged; outside= negatively charged • Difference in charges provides the energy needed to make ATP 6. ATP synthase- protein in membrane • Spins like a turbine • Allows H+ to cross membrane • ATP synthase binds ADP and a phosphate group together to produce ATP

  12. Light-Independent Reaction • Calvin Cycle • Uses ATP and NADPH to produce high-energy sugars • Does not require light

  13. Calvin Cycle • 6 CO2 molecules enter cycle • Combine with 6 5-carbon molecules • Result = 12 3-carbon molecules 2. 3-carbon molecules are converted into higher-energy forms (energy from ATP and NADPH) 3. 2 3-carbon molecules are removed from cycle • Used to produce sugars, lipids, amino acids, etc.. For metabolism and growth of plant

  14. Calvin Cycle 4. Remaining 10 3-carbon molecules are converted back to 6 5-carbon molecules • Combine with 6 new carbon dioxide molecules to begin the next cycle

  15. Factors affecting Photosynthesis • Water • Lack of water can slow or even stop photosynthesis • Desert plants have waxy coating to reduce water loss • Temperature • Enzymes function at particular temp ranges • Intensity of Light • Increasing light increases rate of photosynthesis • There is a maximum rate of photosynthesis

  16. Cellular Respiration • Breakdown of glucose to produce energy • 1g of sugar releases 3811 calories of heat energy • Calorie- amount of energy needed to raise the temp of 1g of water 1˚ Celsius 6O2 + C6H12O6→ 6CO2 + 6H2O + energy • Steps: • Glycolysis • Krebs Cycle • Electron Transport Chain

  17. Glycolysis • Process in which one molecule of glucose is broken in half, producing 2 molecules of pyruvic acid (3-carbon compound) • In cytoplasm • 2 ATP → 4 ATP • NAD+ = electron carrier • Accepts 4 high-energy electrons • Becomes NADH

  18. Glycolysis • Energy yield is small but happens very fast • Does not require oxygen • Problem: NAD+ molecules fill up with electrons; without NAD+ ATP production stops

  19. Fermentation • Releases energy from food molecules by producing ATP in the absence of oxygen • Anaerobic- not in air • 2 main types • Alcoholic fermentation • Lactic acid fermentation • Convert NADH to NAD+ • Allows glycolysis to continue producing a steady supply of ATP

  20. Alcoholic Fermentation • Pyruvic acid + NADH → alcohol + CO2 + NAD+ • Causes bread dough to rise • Yeast in dough runs out of oxygen, begins fermentation which produces CO2

  21. Lactic Acid Fermentation • Pyruvic acid + NADH → lactic acid + NAD+ • Produced in muscles during rapid exercise when the body cannot supply enough oxygen to the tissues • Some unicellular organisms produce lactic acid as a waste product • Cheese, yogurt, buttermilk, sour cream • Pickles, sauerkraut

  22. Krebs Cycle • Pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions • Aerobic- requires oxygen • AKA citric acid cycle – because citric acid is the first compound produced • In mitochondrion

  23. Krebs Cycle

  24. Krebs Cycle • Pyruvate Oxidation: • Pyruvic acid enters mitochondrion • A carbon atom is removed to form CO2 • The other 2 carbon atoms are joined to coenzyme A to form acetyl-CoA A. Acetyl-CoA adds to a 4-carbon molecule producing a 6-carbon molecule called citric acid

  25. Krebs Cycle B. -Citric acid is broken down to produce a 5-carbon chain - CO2 is released - electrons transferred to energy carriers C.- 5-carbon chain is broken down into a 4 carbon chain - CO2 is released - ATP is produced D. – 4 carbon chain is ready to accept acetyl CoA to start cycle all over - FAD is converted to FADH2 - NAD+ is converted to NADH

  26. Electron Transport Chain • Uses high-energy electrons from the Krebs cycle to convert ADP to ATP • In mitochondrion

  27. Electron Transport Chain A.-NADH and FADH2 are passed along ETC and transfer their electrons down ETC • Eukaryotes: membrane of mitochondrion • Prokaryotes: cell membrane • H+ ions are transferred to intermembrane space B.-electrons from ETC combine with H+ ions and oxygen to produce H2O

  28. Electron Transport Chain C. Energy is used to transport of hydrogen ions by 2 high-energy electrons • H+ ions build up in the intermembrane space making it positively charged • The other side of the membrane is negatively charged

  29. Electron Transport Chain D.-Inner membranes of mitochondria contain ATP synthase - ATP spins when H+ ion crosses membrane - While rotating, the enzyme grabs a low-energy ADP and attaches a phosphate producing ATP

  30. Totals • Glucose = 2 ATP • Krebs + ETC = 34 ATP • Total = 36 ATP • Final wastes: water and carbon dioxide

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