Photosynthesis

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Photosynthesis

• Chapter 8

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Trophs

• Autotrophs
• Heterotrophs

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The Meaning of Life
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Photosynthesis

• 6CO2 6H2O C6H12O6 6O2
• Photosynthesis uses the energy of sunlight to
  convert water and carbon dioxide into high-energy
  sugars and oxygen.
• Green things are generally understood to be
  photosynthesizers

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Chlorophyll

• Chlorophyll a
• Chlorophyll b
• Pigments that absorb varying frequencies of
  light.
• Poor absorbers of blue-green frequency

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Chloroplasts

• Thylakoids- contain photosystems which are the
  light-collecting units
• Sunlight excites electrons in the chlorophyll
  which are then passed to electron carriers
• (Sound familiar?)
• NADP is charged with an electron to form NADPH

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Light Dependent Reactions
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Light Dependence

• Two reactions are considered light-dependent in
  photosynthesis
• Photosystem II absorbs light and produces
  energized electrons, H ions, and water.
• Photosystem I receives tired electrons from II,
  are re-energized by sunlight, and used to make
  NADPH which passes to Calvin.

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Mr. Calvin

• ATP and NADPH from the light-dependent reactions
  are used by the Calvin Cycle to create sugars.

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Factors Affecting Photosynthesis

• Water availability
• Sunlight intensity
• Temperature (photosynthetic enzymes function best
  from 0-35 degrees C)
• Light Wavelength

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Back and Forth
6CO2 6H2O C6H12O6 6O2
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O2 sugar
CO2 H2O