Biology - Chp 8 - Photosynthesis - PowerPoint
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Biology - Chp 8 - Photosynthesis - PowerPoint






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    Biology - Chp 8 - Photosynthesis - PowerPoint Biology - Chp 8 - Photosynthesis - PowerPoint Presentation Transcript

    • Picture Guide to Chapter 8 Photosynthesis
    • 8-1 Energy and Life
    • Objectives
      • Explain where plants get the energy they need to produce food
      • Describe the role of ATP in cellular activities
    • Q: Where does energy come from?
      • A: Our food, but originally the energy in food comes from the sun
    • Autotrophs
      • Make their own food
    • Heterotrophs
      • Cannot make their own food
    • Chemical Energy and ATP
      • The principal chemical compounds that cells use to store and release energy is called ATP adenosine triphosphate
    • Storing Energy
      • ATP stores energy in the third phosphate
      • ATP is like a fully charged battery
    • Releasing Energy
      • Q: How is the energy in ATP released?
      • A: Break bond between the second and 3 rd phosphates
      ADP 2
    • Using Biomechanical Energy
      • Active Transport
      • Movement of organelles throughout cell
      • Sythesis of proteins and nucleic acids
      • Produce light
        • Blink of firefly caused by an enzyme powered by ATP
    • ATP Availability
      • Most cells only have enough ATP for a few seconds of activity
      • Why?
        • Not good at storing energy over the long term
        • Glucose stores 90 times the chemical energy of ATP
        • Cells generate ATP from ADP as needed by using the energy in foods like glucose
    • 8-2 Photosynthesis: An Overview
    • Photosynthesis
      • The process in which plants use the energy of sunlight to convert water and carbon dioxide into high energy carbohydrates – sugars and starches – and oxygen as a waste product
    • Photosynthesis
    • The Photosynthesis Equation CO 2 + H 2 O + C 6 H 12 O 6 O 2 light (Carbon Dioxide) (Water) (Sun) (Glucose) (Oxygen)
    • Chlorophyll
      • The plants principal pigment, absorbs light energy in the blue-violet and red spectrum of visible light
    • Absorption of Light by Chlorophyll a and Chlorophyll b Absorption of Light by Chlorophyll a and Chlorophyll b V B G Y O R Chlorophyll b Chlorophyll a
    • Because light is a form of energy…
      • Anything that absorbs light also absorbs the energy from that light
      • When chlorophyll absorbs light, much of the energy is transferred to electrons in the chlorophyll molecule, raising the energy level of these electrons
      • These high-energy electrons make photosynthesis work
    • 8-3 The Reactions of Photosynthesis
    • Thylakoids
      • Sac-like photosynthetic membranes arranged in stacks
    • Grana
      • Stacks of thylakoids
    • Stroma
      • The region outside the thylakoid
    • Scientists describe the reactions of photosynthesis in two parts
      • Light – dependent reactions (takes place in the thylakoid membranes)
      • Light – independent reactions (takes place in stroma)
    • Carrier Molecule
      • Compound that can accept a pair of high energy electrons and transfer them along with most of their energy to another molecule
      • Ex.) NADP+
    • Q: What does this do?
      • NADP+ NADPH
      • A: this traps sunlight in chemical form
    • Light Dependent Reactions
      • Uses energy from light to produce
      • Oxygen gas
      • ATP
      • NADPH
    • The Calvin Cycle
      • The ATP and NADPH formed by the light-dependent reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes.
      • The Calvin cycle uses ATP and NADPH from light – dependent reactions to produce high energy sugars
    • The Calvin Cycle
      • These reactions don’t require light, therefore these reactions are called
      • Light – independent reactions
    • Factors Affecting Photosynthesis
      • Not enough water
      • Temperature
      • Light intensity
    • THE END