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Photosynthesis: Energy and Life

Learn about the process of photosynthesis, where organisms use the sun's energy to make their own food. Understand the role of ATP as the energy currency of the cell and the importance of pigments like chlorophyll. Explore the light and dark reactions of photosynthesis and factors that affect its efficiency.

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Photosynthesis: Energy and Life

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  1. PHOTOSYNTHESIS Chapter 8 Section 1 Pages 201-203

  2. I. Energy & Life A. Autotroph - Organism which uses the sun’s energy to make its own food. B. Heterotroph - Organism which consumes organic material for energy. II. ATP A. ATP (Adenosine Tri-Phosphate) - “Energy currency of the cell.” - When food is broken down, energy is released in the form of ATP.

  3. Example: There is too much energy stored in glucose, so its broken down slowly in order not to lose any energy. This energy is stored in ATP. B. What is Energy? - The ability to do work. C. ATP is a nucleotide. 1. Consists of 3 phosphate groups, the sugar, ribose, and the nitrogen base adenine.

  4. 2. The energy in ATP is stored between the bonds of its phosphate groups. 3. When a -P group is added to another molecule, it will have enough energy to react with other molecules.

  5. Chapter 8: Section 2; Pages 204-207 I. Photosynthesis - Process where energy from the sun, CO2 and water are used to make high-energy sugars. AKA: GLUCOSE II. History of Thought How does a tiny seedling grow until it weighs several tons? 1. Jan van Helmont - Believed plants grew by absorbing water.

  6. 2. Joseph Priestly - Discovered that plants release oxygen. 3. Jan Ingenhousz - Discovered plants only release oxygen in the presence of light.

  7. III. The Photosynthesis Equation A. 6CO2 + 6H2O + Light  C6H12O6 + 6O2 REACTANTS PRODUCTS

  8. IV. LIGHT & PIGMENTS A. Plants also need pigments to undergo photosynthesis. B. Pigments are what absorb energy from the sun. C. A pigment will be the color of the spectrum of light that it CANNOT absorb.

  9. D. The main pigment in plant cells is Chlorophyll. 1. There are two types of Chlorophyll: a. Chlorophyll a - absorbs blue-violet and red light. b. Chlorophyll b - absorbs blue and red light. 2. Green light is not absorbed! E. Plants contain other “Accessory Pigments.”

  10. WHY DO LEAVES CHANGE COLOR?

  11. Chlorophyll: Trees in the temperate zones store these sugars for their winter dormant period. Accessory Pigments: • Carotenoids: which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils, as well as rutabagas, buttercups, and bananas. • Anthocyanins: which give color to such familiar things as cranberries, red apples, concord grapes, blueberries, cherries, strawberries, and plums. They are water soluble and appear in the watery liquid of leaf cells.

  12. Chapter 8: Section 3; Pages 208-214 • Inside a Chloroplast A.Photosynthesis takes place within a chloroplast. B. Chloroplasts contain membranes called “Thylakoids.” 1. A stack of thylakiods is called a “Grana or Granum.”

  13. c. The area outside the thylakoid is called the “Stroma.” 1. Contains liquid which protects and insulates the thylakoids.

  14. Leaf Anatomy • Stomata- pores found on bottom of a leaf to allow CO2 to enter leaves and O2 exit. • Open during the day and closed at night • Why?? • Cuticle- Waxy coating on top of the leaf • Mesophyll- Specialized plant cells containing chloroplasts. • Xylem- carries water absorbed by the roots to the leaves • Phloem- carries sugars made during photo. to the rest of the plant.

  15. II. Light Reactions & Dark Reactions a. Light Reactions (Light Dependent) - Take place within the grana. • 3 raw materials needed are: Light, Water and Chlorophyll. • Uses light energy to convert ADP and • NADP+ (Uncharged Batteries) into the energy carriers ATP and NADPH (Charged Batteries). • 3 products made are: 1 ATP, 2 NADPH and oxygen. • Oxygen is produced as a byproduct and released into the air.

  16. b. The Calvin Cycle (Light – Independent Reactions) - Takes place in the stroma. - Uses ATP and NADPH from the light reactions to produce high-energy sugars such as glucose. - Uses 6 molecules of CO2 to produce one 6-Carbon sugar. - The sugar is either then used for immediate energy or to build larger molecules such as cellulose or starch.

  17. III. Factors Affecting Photosynthesis a. Shortage of water b. Temperature * 32oF to 95oF is what enzymes work best at. c. Light Intensity d. CO2 concentration

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