Photosynthesis!!!!
The Pathway of energy in living organisms
cellular
Chemical
photosynthesis
respiration energy for
Chemical
Light
energy stored in
energy from
use in the
glucose, fats, or
the sun
form of ATP
carbohydrates
Autotrophs = Organisms that make their own food (usually
from photosynthesis).
Heterotrophs = Organisms that can't make their own food
so they take in food produced by autotrophs (by eating
autotrophs or organisms that eat autotrophs)
Overview of Cellular Respiration
C6 H1 2 O6
+
6 O2
Glucose oxygen
6 CO2
carbon
dioxide
+
6H 2 O
+
energy
water
ADP + P + energy
The energy released from the
catabolism of glucose is
used to make ATP from ADP
ATP
Overview of Photosynthesis
6 CO2
+
1 2H2 O
Carbon water
dioxide
+
Solar
energy
C6 H1 2 O6
Glucose
+
6 O2
+
oxygen
The energy from the sun is used to
reduce CO2 to produce glucose
6H 2 O
Figure 10.3 Tracking atoms through photosynthesis
Energy flow and chemical recycling in
ecosystems
Anabolism
Catabolism
Photoautotrophs: other organisms besides plants can
photosynthesize
Photosynthesis is divided into two parts
The overall reaction in
photosynthesis:
6CO2 + 12 H2O + Light
energy
C6H12O6 + 6O2 + 6 H2O
Two components:
Light-dependent reactions
Light
energy
H2O
O2
Chemical
energy
(ATP,
NADPH)
Energy Harvest
Light-independent reactions
Chemical
energy
(ATP,
NADPH)
CO2
Synthesis
Chemical
energy
(C6 H12O6)
The energy from light is captured
and converted in chloroplasts
• Chlorophyll and accessory pigments
capture electromagnetic energy by
absorbing photons of light.
Chlorophyll is found and
Photosynthesis takes place in the
chloroplasts of plant cells
Leaf cross-section
Leaves contain millions of chloroplasts
Cells containing
chloroplasts
Chloroplasts are highly structured,
membrane-rich organelles
Outer
membrane
Inner
membrane
Thylakoids
Granum
Stroma
Inner membrane
Outer membrane
Stroma
Granum
Thylakoid
Figure 10.9 Location and structure of chlorophyll molecules in plants
The energy from the sun arrives on earth in
the form of light energy, a type of
electromagnetic radiation
How objects appear different colors
White light is a mixture of all
wavelengths (and colors) of light
White
light
Green light
Is reflected and transmitted
Red and blue light
Is absorbed
We see the
Plant as green
Figure 10.6 Why leaves are green: interaction of light with chloroplasts
The wavelength of light a compound absorbs can be
determined by a spectrophotometer
Different plant pigments absorb different
wavelengths of light.
Amount of light absorbed
Chlorophyll a
Chlorophyll b
Carotenoids
400
500
600
Wavelength of light (nm)
700
When a photon of light strikes
chlorophyll, an electron can be
promoted to a higher energy state
Electrons can be
promoted to
discrete highenergy states:
e–
Blue photons excite electrons to a
higher energy state
e–
Red photons excite electrons to a
high-energy state
Photons
0
1
Energy state of electrons in chlorophyll
2
Figure 10.10 Excitation of isolated chlorophyll by light
Photosynthesis
• Light Dependent Reaction
– Energy from the high energy electron of
chlorophyll is used to make ATP and NADPH
• Light Independent Reaction (Calvin Cycle)
– ATP and NADPH is used to make glucose from
CO2
Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the
Calvin cycle (Layer 1)
Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the
Calvin cycle (Layer 2)
Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the
Calvin cycle (Layer 3)