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Unit 4 energy
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Unit 4 energy


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  • 1. Unit 4: Energy
  • 2. Energy – What is it? The ability to do work Energy can not be created or destroyed – Energy is TRANSFORMED Forms of energy – Light, electric, chemical Chemical energy is stored in the electrons of chemical bonds
  • 3. Biochemical Energy Cells store and release energy using the chemical ATP – Adenosine triphosphate ATP is the “energy currency” of the cell – MANY cellular processes use ATP Cells release energy by breaking a phosphate bond
  • 4. Photosynthesis Plants convert light energy into chemical energy Energy is stored in the bonds of carbohydrates
  • 5. Light and Pigments Light travels in waves Colors have different wavelengths “White” light is a mixture of all colors in the visible spectrum Red – longest wavelength, lowest energy
  • 6. Light and Pigments Plant pigments absorb sunlight Chlorophyll – green pigment needed for photosynthesis – Reflects green light – Absorbs other light
  • 7. Photosynthesis Overview Reactants: CO2, H2O, light energy Products: O2, C6H12O6 (glucose) Two reactions – Light reaction – Calvin Cycle (light-independent reaction)
  • 8. Chloroplast Structure  Thylakoid sacs contain chlorophyll  Granum – stacks of thylakoids – Light rxn  Stroma – open space – Calvin cycle
  • 9. Photosynthesis Overview
  • 10. Electron Carriers Light energy “excites” electrons in chlorophyll High energy electrons need special carriers – ie: NADP+ and NAD+
  • 11. Light Reaction Chlorophyll absorbs light, and electrons become energized Water splits to produce H+ and O2 Electron loses energy to form ATP – ATP goes to Calvin Cycle H+ and NADP forms NADPH – Carries energy to Calvin Cycle
  • 12. Light Reaction – Electron Transport
  • 13. Light Reaction
  • 14. Light Independent Rxn CO2 is added to a 5 carbon sugar Energy from NADPH & ATP are used to carry out reactions Produces sugar (glucose)
  • 15. Calvin Cycle
  • 16. ATP Revisited How do living things use ATP for energy? Where does ATP come from?
  • 17. Overview of Cellular Respiration 6O2 + C6H12O6  6CO2 + 6H2O + ATP
  • 18. Overview of Cellular Respiration  Energy from glucose is released – In the presence of O2 – Energy is stored in ATP – CO2 is a byproduct  3 Stages – Glycolysis – Krebs Cycle – Electron Transport Chain
  • 19. Glycolysis In the cytoplasm Glucose breaks into 2 molecules of pyruvic acid (3C) Uses 2 ATP, produces 4 ATP – Net gain of 2 ATP  2 NADH produced  Pyruvic acid is used for respiration OR fermentation
  • 20. Krebs Cycle  In the mitochondria  Pyruvic acid breaks down  Series of 9 rxns which produce: – CO2 – FADH2 and NADH – 2 ATP  FADH2 and NADH go on to the ETC to…. – MAKE MORE ATP!!!!
  • 21. Electron Transport Chain  Occurs in mitochondria  Uses high energy electrons from FADH2 and NADH to make ATP  O2 accepts the final electron forming H2O
  • 22. Page 229 The Totals Electron carriers which go on the electron transport chain to generate ATP!
  • 23. 2 2 32
  • 24. Fermentation Releases energy from food in the absence of O2 2 Types – Alcoholic – produces ethanol and CO2 • Yeast, bacteria – Lactic Acid – produces lactic acid • Muscle cells, bacteria