1. 8-3 The Reactions of Photosynthesis
Photo Credit: ©Stone
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Inside a Chloroplast
Parts of plant involved in photosynthesis:
Stomata-On outside of plant leaf—allows for oxygen and carbon dioxide exchange….like a plant’s mouth
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Inside a Chloroplast
Chloroplasts contain thylakoids—saclike photosynthetic membranes. This is where the light dependent reaction takes place.
Single
thylakoid
Chloroplast
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Inside a Chloroplast
Thylakoids are arranged in stacks known as grana. A singular stack is called a granum.
Granum
Chloroplast
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Inside a Chloroplast
Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters called photosystems, which are the light-collecting units of the chloroplast.
Photosystems
Chloroplast
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Inside a Chloroplast
Stroma – fluid portion inside chloroplast where light-independent reactions occur
Stroma
Chloroplast
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Electron Carriers
Electron Carriers
When electrons in chlorophyll absorb sunlight, the electrons gain a great deal of energy.
Cells use electron carriers to transport these high-energy electrons from chlorophyll to other molecules.
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Electron Carriers
One carrier molecule is NADP+.
Electron carriers, such as NADP+, transport electrons.
NADP+ accepts and holds 2 high-energy electrons along with a hydrogen ion (H+). This converts the NADP+ into NADPH.
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10. Light-Dependent Reactions
The light-dependent reactions require light.
The light-dependent reactions use light energy to make two molecules needed for the next stage of photosynthesis. Using light energy and water, ATP and NADPH are made and oxygen is released.
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12. Photosystem II captures and transfers energy (in thylakoid)

13. Photosystem I captures energy and produces energy-carrying molecules.

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SO the products of the light dependent reactions are:
Oxygen
ATP and NADPH (to make sugars in the Calvin Cycle)
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15. 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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The Calvin Cycle
What is the Calvin cycle (Light Independent Reaction)?
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The Calvin Cycle
The Calvin cycle uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars.
Because the Calvin cycle does not require light, these reactions are also called the light-independent reactions.
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The Calvin Cycle
1. Carbon dioxide molecules (that we have exhaled) enter the Calvin cycle
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
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The Calvin Cycle
2. Energy is added (ATP and NADPH from light reactions) and carbon molecules are rearranged
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
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The Calvin Cycle
3. Two high-energy three-carbon molecule make a sugar = C6H12O6
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
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The Calvin Cycle
4. Plants use the sugars, proteins, and lipids as energy
The Calvin cycle uses ATP and NADPH to produce high-energy sugars.
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23. 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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SO the product of the light independent reactions or Calvin Cycle is:
Glucose = sugar for the plant = C6H12O6 because they produce their own food (the C comes from CO2)
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The two sets of photosynthetic reactions work together.
The light-dependent reactions trap sunlight energy in chemical form, breaking the water molecules and releasing oxygen.
The light-independent reactions use that chemical energy to produce stable, high-energy sugars from carbon dioxide and water.
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Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize glucose from carbon dioxide and water. The sunlight’s energy is similar to a power plant that provides energy. The removal of the water and minerals from the soil is like heavy equipment removing raw materials from the earth. The process involves green pigment chlorophyll, which is found in chloroplasts. Like a food factory, plants produce carbohydrates for use and store the starch and sugar in the plant for energy. The process generates oxygen as a byproduct.
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8-3
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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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