1. 8-3 The Reactions of Photosynthesis
Photo Credit: ©Stone
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Inside a Chloroplast
Inside a Chloroplast
Photosynthesis takes place inside chloroplasts.
Plant
Chloroplast
Plant cells
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Inside a Chloroplast
Chloroplasts contain thylakoid membranes.
Single
thylakoid
Chloroplast
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Inside a Chloroplast
Grana are stacks of thylakoids.
Granum
Chloroplast
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Inside a Chloroplast
Photosystems are the light-collecting units of the chloroplast.
Contain chlorophyll.
Photosystems
Chloroplast
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Inside a Chloroplast
Phases of Photosynthesis:
Light reaction
Dark reaction (Calvin cycle)
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7. Light- dependent reactions
Inside a Chloroplast
H2O
CO2
Light
NADP+
ADP + P
Light- dependent reactions
Calvin Cycle
Calvin cycle
The process of photosynthesis includes the light-dependent reactions as well as the Calvin cycle.
Chloroplast O2
Sugars
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Light Reaction
Light Reactions:
Chlorophyll absorbs light (energized)
ATP is produced
Water is split into Hydrogen & Oxygen
Oxygen is released into the atmosphere
NADPH transports Hydrogen atoms
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The Calvin Cycle
Calvin Cycle:
NADPH + ATP + CO2 produce 2 molecules of PGAL
2 PGAL’s form one glucose molecule
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The Calvin Cycle
Six carbon dioxide molecules enter the cycle from the atmosphere and combine with six 5-carbon molecules.
CO2 Enters the Cycle
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
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The Calvin Cycle
The result is twelve 3-carbon molecules, which are then converted into higher-energy forms.
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
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The Calvin Cycle
The energy for this conversion comes from ATP and high-energy electrons from NADPH.
Energy Input 12
12 ADP 12
NADPH
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
12 NADP+
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The Calvin Cycle
Two of twelve 3-carbon molecules are removed from the cycle.
Energy Input 12
12 ADP 12
NADPH
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
12 NADP+
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14. 6-Carbon sugar produced Sugars and other compounds
The Calvin Cycle
The molecules are used to produce sugars, lipids, amino acids and other compounds. 12
12 ADP 12
NADPH
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
12 NADP+
6-Carbon sugar produced
Sugars and other compounds
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15. 5-Carbon Molecules Regenerated Sugars and other compounds
The Calvin Cycle
The 10 remaining 3-carbon molecules are converted back into six 5-carbon molecules, which are used to begin the next cycle. 12
12 ADP
6 ADP 12
NADPH 6
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
12 NADP+
5-Carbon Molecules Regenerated
Sugars and other compounds
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The Calvin Cycle
Factors Affecting Photosynthesis
Many factors affect the rate of photosynthesis, including:
Water & Carbon Dioxide
Temperature & pH
Intensity of light
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8-3
In plants, photosynthesis takes place inside the
thylakoids.
chloroplasts.
photosystems.
chlorophyll.
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8-3
Energy to make ATP in the chloroplast comes most directly from
hydrogen ions flowing through an enzyme in the thylakoid membrane.
transfer of a phosphate from ADP.
electrons moving through the electron transport chain.
electrons transferred directly from NADPH.
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8-3
NADPH is produced in light-dependent reactions and carries energy in the form of
ATP.
high-energy electrons.
low-energy electrons.
ADP.
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8-3
What is another name for the Calvin cycle?
light-dependent reactions
light-independent reactions
electron transport chain
photosynthesis
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8-3
Which of the following factors does NOT directly affect photosynthesis?
wind
water supply
temperature
light intensity
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