PHOTOSYNTHESIS
Photosynthesis
• Process that requires carbon dioxide
(CO2), light energy (photons), and
water (H2O) to produce organic
macromolecules (glucose).
SUN
photons
6CO2 + 6H2O  C6H12O6 + 6O2
glucose
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Question:
Where does
photosynthesis
take place?
3
Plants
• Autotrophs – produce their own food
(glucose)
• Process called photosynthesis
• Mainly occurs in the leaves:
a. stoma - pores
b.mesophyll cells
Mesophyll
Cell
Chloroplast
Stoma
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Stomata (stoma)
Pores in a plant’s cuticle through
which water vapor and gases (CO2
& O2) are exchanged between the
plant and the atmosphere.
Stoma
Carbon Dioxide
(CO2)
Guard Cell
Oxygen
(O2)
Guard Cell
Found on the underside of leaves
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Mesophyll Cell of Leaf
Nucleus
Cell Wall
Chloroplast
Central Vacuole
Photosynthesis occurs in these cells!
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Chloroplast
Organelle where photosynthesis
takes place.
Stroma
Outer Membrane
Inner Membrane
Thylakoid
Granum
Thylakoid stacks are connected together
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Thylakoid
Thylakoid Membrane
Granum
Thylakoid Space
Grana make up the inner membrane
9
Question:
Why are
plants
green?
10
Chlorophyll Molecules
• Located in the thylakoid membranes
• Plants are green because the green
wavelength is reflected, not absorbed.
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Question:
During the fall,
what causes the
leaves to change
colors?
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Fall Colors
• In addition to the chlorophyll
pigments, there are other pigments
present
• During the fall, the green
chlorophyll pigments are greatly
reduced revealing the other pigments
• Carotenoids are pigments that are
either red, orange, or yellow
13
Question:
What do
cells use
for energy?
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Energy for Life on Earth
• Sunlight is the ULTIMATE
energy for all life on Earth
• Plants store energy in the
chemical bonds of sugars
• Chemical energy is released as
ATP during cellular respiration
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High Energy Phosphate Bond
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Parts of
Photosynthesis
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Two Parts of Photosynthesis
Two reactions make up
photosynthesis:
1.Light ReactionsProduces energy from solar
power (photons) in the form of
ATP and NADPH.
SUN
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Two Parts of Photosynthesis
2. Calvin Cycle
• Uses energy (ATP and
NADPH) from light reaction
to make sugar (glucose).
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Stage 1: Light Reactions
• Where do they occur?
Thylakoid membranes
• What is the starting molecule?
Water
• What are the end products?
Oxygen, ATP, NADPH
• This stage requires light!
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Calvin Cycle FYI
• Occurs in the stroma
• Uses ATP and NADPH from light
reaction as energy
• Uses CO2
• To produce glucose: it takes 6
turns and uses 18 ATP and 12
NADPH.
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Stage 2: Calvin Cycles
• Where do they occur?
Stroma
• What is the starting molecule?
Carbon dioxide (CO2), ATP, and
NADPH
• What are the end products?
Glucose
• This stage does not require light!
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Chloroplast
Outer Membrane
Inner Membrane
STROMA– where Calvin Cycle occurs
Thylakoid
Granum
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The overall equation for
Photosynthesis
• 6CO2 + 6H2O + light energy  C6H12O6 + 6O2
• In words:
• Carbon dioxide + water + light energy 
Glucose + oxygen
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Photosynthesis