FADS
Modern Chlorophyll-Enriched Products
Why Don’t Chlorophyll Enriched Products
Provide You With More Energy?
Photosynthesis Requires More Than
Just Pigments. It Needs Organelles and
Enzymes To Control the Reaction
Photosynthesis
• What: Synthesis of carbohydrates from
CO2 and Water using the energy of the
sun
• Why: To provide sugars for the cells to use
for energy flow (i.e. cellular respiration)
• Where: The chloroplast
• When: Light and dark
• How: Two separate reactions
– Photolysis (light dependent reactions)
– Calvin-Benson Cycle (light independent
reactions)
Photolysis
• What: Making ATP
and providing
hydrogen for The
Dark Reactions
• Where: Thylakoid
Membranes of
Chloroplast
• Who: Light, Pigments,
Water and NADP (to
carry hydrogen)
Photolysis
(aka The Light Dependent Reactions)
• Light strikes accessory pigments in
photosystem, exciting their electrons
• Electrons are passed on to chlorophyll, whose
electrons are additionally photoexcited
• The energy from photoexcitation is used to
rebuild ATP from ADP
• Without photolysis, there would be no ATP
for building glucose (i.e. Calvin-Benson Cycle)
Why is water necessary?
• When chlorophyll is excited, it loses
electrons and starts to break down
• To replace these electrons and preserve
chlorophyll, water molecules break apart,
providing electrons to “save” chlorophyll
• Giving up electrons causes water to “split”
into oxygen gas (O2) and hydrogen
• The hydrogen ions are picked up by NADP
and carried to the Dark Reactions
If chlorophyll absorbs all colors of spectrum except
for green, why do the leaves of deciduous trees
change color in the fall?
Chlorophyll & Fall
• Chlorophyll requires a
great deal of ATP and
water to synthesize
• In the fall, there is
less water available to
make chlorophyll and
less available light to
use for synthesis
• As a result, leaves
stop producing
chlorophyll
Calvin-Benson Cycle
• What: Synthesis of
glucose
• When: Independent of
light
• Where: Stroma (gellike interior of
chloroplast)
• Who: CO2, Rubisco,
NADPH, ATP
Major Actions of Calvin-Benson Cycle
• 1) CO2 enters the leaf via the stomata
• 2) Carbon Dioxide (CO2) is “fixed”/removed from
air via the enzyme Rubisco.
• 3) NADPH gives up its hydrogen to CO2 in a
series of cyclical, enzymatically controlled
reactions
• 4) Glucose is synthesized
Why can’t you do the Calvin
Benson Cycle without Photolysis?
Global Warming & Calvin-Benson Cycle
Review of Photosynthesis
• PHOTOLYSIS
•
•
•
•
•
• THE CALVIN CYCLE
aka The Light Dependent
• aka The Light
Reactions
Independent/Dark
Occurs in grana of
Reactions
chloroplast
• Occurs in stroma
Depend upon light energy to
• Do not require light
accelerate electrons of
pigments
• Using the ATP from the
photolysis, the Calvin
ATP is produced to power 2nd
set of reactions
Cycle “fixes” Carbon
Dioxide by combining it
Water replaces electrons lost
with hydrogen to make
by chlorophyll. This causes
water to split, releasing
glucose
oxygen gas.
• Leftover hydrogen is used to
build glucose