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Energy in Living Systems

Energy in Living Systems. CH 6 pg 112-118. Organisms classified on how they obtain energy. Autotrophs Make their own food from organic molecules Most convert light energy into chemical energy Carbon Dioxide (CO 2 ) and water (H 2 O) to organic compound Oxygen (O 2 ) released Heterotrophs

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Energy in Living Systems

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  1. Energy in Living Systems CH 6 pg 112-118

  2. Organisms classified on how they obtain energy • Autotrophs • Make their own food from organic molecules • Most convert light energy into chemical energy • Carbon Dioxide (CO2) and water (H2O) to organic compound • Oxygen (O2) released • Heterotrophs • Cannot make their own food inorganic compounds • Eat autotrophs or other heterotrophs

  3. Photosynthesis

  4. Harvesting Light Energy • Photosynthetic organisms have chloroplasts • Chloroplasts are the organelles that convert light energy into chemical energy. • Contains flat, disc-like sacs called thylakoids. • this is the first stage of photosynthesis.

  5. Thylakoids

  6. Light Absorption in Chloroplast • Sunlight composed of ROY G BIV, different colors. (Lgth = Amt of Engy) • Color observed when light strikes an object, waves are reflected, transmitted, or absorbed • Colors react depending on the pigment present

  7. Harvesting Light Energy, continued • Chlorophyll (a and b) • Absorbs blue and red light and reflects green and yellow light • Carotenoids • help plants absorb additional light energy • absorb blue and green light, reflect red, orange and yellow(fallcolors)

  8. Two Electron Transport Chains • First reaction in photosynthesis is the light reaction takes place in the chlorophyll • Light hits a thylakoid • Energy is absorbed by the pigment molecules and are directed to a special chlorophyll molecule that acts as a reaction center • Electrons are excited and move to other molecules and the electron transport chain. • One ETC makes ATP and Second makes NADPH

  9. Understanding Terms • Photosystem II (ETC #1) • Products: Electron, Oxygen (pg 117) ATP (pg 118) • Photosystem I (ETC#2) • Products: NADPH • Light Reaction (Electron Transport Chains) create energy molecules for the Calvin Cycle

  10. 1st Electron Transport Chain Producing ATP Step 1: • An enzyme splits water molecules , e- is released. • H+ ions stay within the thylakoid • e- is charged by pigment • Oxygen gas is released into the atmosphere

  11. Step 2: • Carrier Proteins (ATP Synthase) in the membrane pump H+ ions into the thylakoid,

  12. Step 3: • Energy diffusion of H+ ions through ATP synthase is used to make ATP

  13. 2nd Electron Transport Chain Step 4:Producing NADPH • Renergizing, Light excites electrons that are passed on to the second chain.

  14. Step 5: Making NADPH • Excited electrons combine with H+ ions and NADP+ to form NADPH. • NADPH is used to store energy in organic molecules. (used later in dark reaction)

  15. Electron Transport Chains of Photosynthesis Click to animate the image.

  16. Producing Sugar • The first two stages of photosynthesis depend directly on light to make ATP and NADPH. • In the final stage of photosynthesis, ATP and NADPH are used to produce energy-storing sugar molecules from the carbon in carbon dioxide. • The use of carbon dioxide to make organic compounds is called carbon dioxide fixation, or carbon fixation. (Light Independent, Dark Reaction, or Calvin Cycle)

  17. Calvin Cycle • Takes place outside of the Thylakoid in the stroma • solution surrounding the thylakoid • Carbon Fixation, CO2 is being used to make G3P • Enzyme Rubisco adds CO2 to RuBP to create G3P which is later used to make a sugar (Glucose or C6H1206)

  18. What is happening in the Calvin Cycle?This is what you need to know • Part 1 Carbon Fixation • Carbon dioxide (from the atmosphere) diffuses into the plant cell and enters the stroma of the chloroplast • Rubisco (an enzyme) attaches CO2 to RuBP  as a result of this chemical reaction is now known as molecule PGA. • Write Rubisco on illustration by carbon fixation

  19. Part 2 Reduction • PGA uses the energy molecules (ATP, NADPH) to create G3P • ETC #1 and #2 (light reaction) create ATP and NADPH • Energy is released from the hydrogen and phosphate bonds to drive a reaction creating G3P • NADP and ADP are then recycled in the stroma to be used again in the ETC

  20. Rengeneration of Ribulose (RuBP) • Step 3 • Some of the G3P molecules are then used to make glucose • Transported out of the chloroplast • Step 4 • Other G3P molecules are recycled into making RuBP • In order to continue the Calvin Cycle

  21. Factors that Affect Photosynthesis • Light intensity (ATP and NADPH) • Carbon dioxide concentration • Temperature (function of enzymes)

  22. Relationship

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