Photosynthesis!!!!

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Photosynthesis!!!!
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The Pathway of energy in living organisms
cellular respiration
Chemical energy for use in the form of ATP
photosynthesis
Light energy from the sun
Chemical energy stored in glucose, fats, or
carbohydrates
Autotrophs Organisms that make their own food
(usually from photosynthesis). Heterotrophs
Organisms that can't make their own food so they
take in food produced by autotrophs (by eating
autotrophs or organisms that eat autotrophs)
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Overview of Cellular Respiration
ADP P energy
The energy released from the catabolism of
glucose is used to make ATP from ADP
ATP
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Overview of Photosynthesis
The energy from the sun is used to reduce CO2 to
produce glucose
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Figure 10.3 Tracking atoms through photosynthesis
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Energy flow and chemical recycling in ecosystems
Anabolism
Catabolism
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Photoautotrophs other organisms besides plants
can photosynthesize
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Photosynthesis is divided into two parts
The overall reaction in photosynthesis
Light energy
12 H2O
6CO2
C6H12O6
6O2
6 H2O




Two components
Light-dependent reactions
Light-independent reactions
Chemical energy (ATP, NADPH)
Chemical energy (ATP, NADPH)
Chemical energy (C6 H12O6)
Light energy
O2
H2O
CO2
Energy Harvest
Synthesis
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The energy from light is captured and converted
in chloroplasts

• Chlorophyll and accessory pigments capture
  electromagnetic energy by absorbing photons of
  light.

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Chlorophyll is found and Photosynthesis takes
place in the chloroplasts of plant cells
Leaf cross-section
Cells containing chloroplasts
Leaves contain millions of chloroplasts
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Chloroplasts are highly structured, membrane-rich
organelles
Outer membrane
Inner membrane
Stroma
Granum
Thylakoid
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Figure 10.9 Location and structure of
chlorophyll molecules in plants
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The energy from the sun arrives on earth in the
form of light energy, a type of electromagnetic
radiation
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How objects appear different colors
White light is a mixture of all wavelengths (and
colors) of light
White light
Green light Is reflected and transmitted
We see the Plant as green
Red and blue light Is absorbed
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Figure 10.6 Why leaves are green interaction of
light with chloroplasts
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The wavelength of light a compound absorbs can be
determined by a spectrophotometer
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Different plant pigments absorb different
wavelengths of light.
Chlorophyll a
Chlorophyll b
Carotenoids
Amount of light absorbed
400
600
500
700
Wavelength of light (nm)
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When a photon of light strikes chlorophyll, an
electron can be promoted to a higher energy state
Electrons can be promoted to discrete high-energy
states
e
Blue photons excite electrons to a higher energy
state
e
Red photons excite electrons to a high-energy
state
Photons
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1
2
Energy state of electrons in chlorophyll
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Figure 10.10 Excitation of isolated chlorophyll
by light
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Photosynthesis

• Light Dependent Reaction
• Energy from the high energy electron of
  chlorophyll is used to make ATP and NADPH
• Light Independent Reaction (Calvin Cycle)
• ATP and NADPH is used to make glucose from CO2

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Figure 10.4 An overview of photosynthesis
cooperation of the light reactions and the Calvin
cycle (Layer 1)
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Figure 10.4 An overview of photosynthesis
cooperation of the light reactions and the Calvin
cycle (Layer 2)
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Figure 10.4 An overview of photosynthesis
cooperation of the light reactions and the Calvin
cycle (Layer 3)