Transcript The Process of Photosynthesis

The Process of Photosynthesis
Photo = Light
Synthesis = To Make
• Light energy is converted to chemical bond
energy. With this energy the chemical bonds of
carbon dioxide and water are broken and
reassembled into carbohydrates. In this
process oxygen is also produced.
Photosynthetic Organisms: Photoautotrphs
• Cyanobacteria,
algae, protists, as
well as plant are
all capable of
conducting
photosynthesis.
• Most of the
photosynthesis
on Earth is
carried out by
phytoplankton
In Plants Photosynthesis Occurs In the
Chloroplasts Within the Leaves
The Nature of Light
Photons are discreet packets of light energy made in the sun that travel
in waves of different lengths. Visible light is composed of wavelengths
ranging from 380 to 750 nanometers. Photosynthetic pigments convert
some of these visible light wavelengths into chemical energy. For
Photosynthesis, light energy from the blue and red portions of the
spectrum are converted to chemical bond energy.
• Pigments absorb
certain wavelengths of
light and convert their
energy into chemical
energy.
• Pigments reflect or
transmit wavelengths
of light energy that they
do not convert to
chemical energy,
therefore, they appear
this color.
• Chlorophyll is green,
therefore, it absorbs
blue and red
wavelengths of light
Chloroplasts Have
the Green Pigment
Chlorophyll
Redox Reactions
• During photosynthesis light energy is converted
to chemical energy which drives the redox
reaction above.
• Reduction occurs when atoms of molecules gain
electrons and become more complex.
• Oxidation occurs when atoms of molecules lose
electrons and are simplified.
Photosynthesis/Respiration
Matter Recycled, Energy Transformed
• Photosynthesis:
6CO2 + 6H2O   C6H12O6 + 6O2
• Respiration:
C6H12O6 + O2   6CO2 + 6H2O
Notice that the products of photosynthesis are the reactants of respiration and the
products of respiration are the reactants of photosynthesis, in this way matter is
recycled.
Energy comes from the sun, it is transformed during photosynthesis to chemical
energy in the bonds of food and then through cellular respiration into ATP.
Photosynthesis: Two Reactions: Light
Dependent and Light Independent
Light Dependent Reaction
During the light dependent reaction three main events occur as solar energy is transformed:
1. Water is split into hydrogen and oxygen (Photolysis). This is the source of atmospheric oxygen.
2. NADP+ is reduced to NADPH (with the H+ that comes from photolysis)
3. ADP + P → ATP (Photophosphorilation)
Calvin Cycle Is Light Independent
• During the light independent reaction, ATP (formed during
photophosphorilation) provides the energy to “fix” carbon
dioxide (reduced it with hydrogen donated by NADPH formed
in the light dependent reaction) to form carbohydrates.
Photosynthesis Summary
Light Reaction:
•Photolysis H2O  H+ + O2
•NADP+ + H  NADPH
•ADP + P  ATP
Dark Reaction:
•CO2 + NADPH + ATP 
Carbohydrate CN(H2O)N
Producers: Produce Food
• Photoautotrophs produce “food” which is
consumed directly or indirectly by organisms at
all trophic levels of a food chain/ web.
Producers: Produce Oxygen
• Photoautotrophs, produce oxygen through
photolysis.
• This oxygen becomes atmospheric oxygen gas
– Ozone layer
– Oxygen for aerobic cellular respiration
To Counteract the Greenhouse Effect:
Plant a Tree
Carbon Dioxide is one of the component gases of the “greenhouse” gas layer, which traps
reradiated solar radiation near the surface of our planet and increases global warming.
The more photosynthesis that takes place on our planet, the more carbon dioxide that is
consumed in the photosynthetic process and the less carbon dioxide available to the
greenhouse gas layer . PLANT A TREE TO COMBAT GLOBAL WARMING!!!
To Counteract Ozone Holes: Pant a Tree
• The ozone layer in the
stratosphere is made up of
oxygen.
• It shields the planet against
the damaging effects of
ultraviolet radiation and other
forms of solar radiation which
increase global warming.
• Holes in the ozone layer
caused by anthropogenic
pollution can be patched up
with atmospheric oxygen.
• Increasing photosynthetic
output will increase
atmospheric oxygen and help
to repair the ozone layer.
Human legacy is the sustainability of life on Earth
G. Inguanzo Jr. Appalachian Blue Ridge Habersham County Georgia 2006