Light dependent Reaction, Calvin Cycle

1. PHOTOSYNTHESIS
JANET BRIGIDA A. CATIPON
MHS SCIENCE TEACHER
MAE-CHEMISTRY, BSU

2. LESSON’S OBJECTIVES
To identify the structures involved in the food making
process in plants
To identify the raw materials and end products of
Photosynthesis
To understand the process of Food Making of Plants

3. MODULE 4
ECOSYSTEM:
Life Energy
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4. WHEREDOESPHOTOSYNTHESISTAKEPLACE?
Inside the leaves of
plants
The Chloroplast
Thylakoid Membrane of
Chloroplast
Stroma of the Chloroplast

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Life Energy
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Chlorophyll
THE CHEMICAL PROCESS

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INTERNAL STRUCTURE OF A LEAF
Guard Cell
Cuticle
Cuticle
Mesophyll
Cells
Upper Epidermis
Chloroplasts
Palisade
Parenchyma
Xylem
Phloem
Lower Epidermis
Spongy Mesophyll

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THE CHLOROPLASTS
OUTER MEMBRANE
INTERMEMBRANE SPACE
INNER MEMBRANE
GRANUM
LAMELLA
LUMEN

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INSIDE THE THYLAKOID MEMBRANE
THE FIRST STAGE OF PHOTOSYNTHESIS TAKES PLACE
CALLED PHOTOSYSTEM I – LIGHT DEPENDENT
REACTION.
It happens in the presence of light.
It occurs inside the thylakoid membrane and converts
light energy to chemical energy.
Absorbed water through the roots of plants is utilized
and facilitates the formation of the electrons and
oxygen.
The energy harvested in this stage is stored in the
form of ATP ( Adenine Triphosphate) and NADPH
(Nicotinamide Adenine Diphosphate Hydrogen)
ATP and NADPH will be needed in the 2nd stage of
Photosynthesis ( Photosystem II) called the Calvin
Cycle or Dark Reaction (Light Independent Reaction.

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INSIDE THE THYLAKOID MEMBRANE

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IN THE STROMA
THE SECOND STAGE OF PHOTOSYNTHESIS TAKES PLACE
CALLED THE CALVIN CYCLE - LIGHT INDEPENDENT
REACTION OR DARK REACTION.
It happens in the STROMA of Chloroplast where the Carbon
Dioxide absorbed by the leaves of the plant is converted into
sugar.
The reaction does not require light from the sun.
The reaction is divided into three main stages: carbon fixation,
reduction, and regeneration of the starting molecule.
In fixation, the first stage of the Calvin cycle, light-independent
reactions are initiated; CO2 is fixed from an inorganic to an
organic molecule.
In the second stage, ATP and NADPH are used to reduce 3-PGA
into G3P; then ATP and NADPH are converted to ADP and
NADP+, respectively.
In the last stage of the Calvin Cycle, RuBP is regenerated, which
enables the system to prepare for more CO2 to be fixed.

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THE CALVIN CYCLE

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STAGES OF PHOTOSYNTHESIS

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IMPORTANT TERMS
3PGA 3-phosphoglyceric acid
RuBP ribulose1,5-biphosphate. an organic
substance that is involved in photosynthesis,
reacts with carbon dioxide to form 3-PGA
RuBisCo a plant enzyme which catalyzes the fixing of
atmospheric carbon dioxide during
photosynthesis by catalyzing the reaction
between carbon dioxide and RuBP.
ATP Adenine Triphosphate
NADPH Nicotinamide Adenine Diphosphate Hydrogen
ADP Adenine Diphosphate
NADP Nicotinamide Adenine Diphosphate
Carbon Fixation refers to the conversion process of
inorganic carbon (carbon dioxide) to organic
compounds by living organisms.
Reduction Reduction phase of Calvin Cycle –uses
NADPH, ATP, and carbon dioxide (which
enters from atmosphere intochloroplast at this
time) to make glucose
Regeneration With 3molecules of ATP, the remaining
five G3P molecules remain in the cycle and
are used to regenerate RuBP, which enables
the system to prepare for more CO2 to be fixed.