Download Photosynthesis - Piscataway High School

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All Living Things….

Need Energy to survive.
–
Energy allows you to do work and run chemical reactions.


Energy is stored in chemical bonds.
Breaking bonds releases energy!
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Where do organisms get energy?
Autotrophs – make their own food
•Phototrophs make food using sunlight
•Chemotrophs make food using chemicals
Heterotrophs – eat to get energy
•Herbivores eat plants
•Carnivores eat other animals
•Omnivores eat plants and animals
•Decomposers eat dead material
Are plants autotrophs or heterotrophs?
Are plants phototrophs or chemotrophs?
What is ATP?
-A high energy molecule used by cells to do work or drive chemical reactions.
-ATP is made and used during photosynthesis.
What is sunlight?
Sunlight is composed of waves of energy called photons.
When these waves hit an atom, they can increase the
energy of its electrons.
These waves have a length and the length determines
its color.
Sunlight
(white
light)
Actually made of
colored lights of
various
wavelengths.
Chlorophyll:
green pigment (light absorbing molecule)
found in chloroplasts of eukaryotic cells
REFLECTS green wavelengths, absorbs all others
Chlorophyll Doesn’t Absorb Green Light
(it reflects it!)
What causes Autumn Colors?
Carotenoids- pigments that reflect yellow and
orange colors
When fall comes the chlorophyll in the leaves
begins to break down and exposes the carotenoids,
causing the leaves to appear red, yellow, and
orange!
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What do autumn leaves &
ripening bananas have in
common?
The green color in unripe bananas comes
from chlorophyll, the same pigment that
gives green leaves their color.
As bananas ripen, the chlorophyll breaks down and
disappears, revealing the yellow color which has been
there all along.
The yellows and oranges of autumn leaves are also
revealed as their chlorophyll breaks down.
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Photosynthesis
-changing the energy from sunlight
into chemical energy (glucose)
Chloroplast
Space between
the grana
photosynthetic
membrane sack
Photosystems:
light collecting units in the thylakoid membrane
(clusters of proteins and pigments)
What happens in photosynthesis?
Photosynthesis Has Two Parts
1. Light Reaction- in the thylakoid membrane
2. Dark Reaction (Calvin Cycle)- in the stroma
Dark Reaction
Light Reaction
Light Reaction
H2O + NADP+ + ADP + P
O2 + NADPH + ATP
LIGHT
Light Reaction
1) Chlorophyll electrons are pushed to
higher energy levels by sunlight.
H2O
2) Water molecules are split into 3 parts
-oxygen is released into the air
O2
e-electrons released to restore chlorophyll
-hydrogen ions build up inside the thylakoid
H+
3) NADP+ + H+ + electrons
4) ADP + P
NADPH
ATP
Light Reaction
Animations
http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120072/bio13.swf
::Photosynthetic%20Electron%20Transport%20and%20ATP%20Synthesis
ATP Synthetase
Protein in the membrane of the thylakoid.
lets H+ back into the stroma and
ADP + P
ATP
https://www.youtube.com/watch?v=3y1dO4nNaKY
The Light Reaction
H2O + NADP+ + ADP + P
LIGHT
O2 + NADPH + ATP
High energy compounds
needed for the dark reaction
Almost all oxygen in atmosphere comes from splitting
water in Light Reaction of photosynthesis!!!!!
The Dark Reaction (Calvin Cycle)
6CO2 + 18ATP + 12NADPH
C6H12O6 + 18ADP + 12NADP+ + 18 P
The Dark Reaction
-doesn’t need light
-in stroma of chloroplast
-use the ATP and NADPH from the light reactions
AKA:
Carbon
Fixation
- CO2 is taken from air and used to make glucose
C enters as CO2 and leaves as glucose
Balanced Equation for Photosynthesis
6CO2 + 6H2O


used in the
used in the
“dark” reactions “light” reactions
C6H12O6 + 6O2

produced in the
“dark” reactions

produced
in the
“light”
reactions
Why do the dark reaction at all?
ATP is not a stable energy source.
For long term energy storage, glucose and
starch made from glucose are more stable
options.
The Ins and Outs of
Photosynthesis
Location
Reactant
Product
Light
Reaction
Dark
Reaction
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The Ins and Outs of
Photosynthesis
Location
Light
Reaction
Reactant
Thylakoid
Membrane
Product
Light
O2
 H 2O
NADPH
NADP+
ATP
ADP + P
Dark
Reaction
Stroma
NADPH
NADP+
ATP
ADP + P
CO2
glucose
LIGHT
6 CO2 + 6 H2O
C6H12O6 + 6 O2
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Environmental Factors and
Photosynthesis
Light
as it increases,
photosynthesis
increases then
levels off
CO2
as it increases,
photosynthesis
increases then
levels off
Temperatureas it increases,
photosynthesis peaks
then decreases,
enzymes denatured,
stomata close
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Why are leaves Green?

Leaves are green because of the pigments called
chlorophyll found in their chloroplasts.
Chlorophyll  absorbs light very well in the
blue-violet and red regions of the visible
light spectrum.
It reflects the green color that you see!
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What is ATP?
-A high energy molecule used by cells to do work or drive chemical reactions.
-ATP is made when bonds are broken or in photosynthesis
Energy is released when
this bond is broken.