Transcript Photosynthesis

THE SUN: MAIN SOURCE OF
ENERGY FOR LIFE ON EARTH
THE BASICS OF PHOTOSYNTHESIS
• All plants are photosynthetic autotrophs, as are
some bacteria and some protists
– These autotrophs generate their own organic matter
through photosynthesis
– Sunlight energy is transformed to energy stored in the
form of chemical bonds
(c) Euglena
(b) Kelp
(a) Mosses, ferns, and
flowering plants
(d) Cyanobacteria
Light Energy Harvested by Plants &
Other Photosynthetic Autotrophs
6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
Food Chain
THE FOOD WEB
AN OVERVIEW OF PHOTOSYNTHESIS
• Photosynthesis is the process by which
autotrophic organisms use light energy to
make sugar and oxygen gas from carbon
dioxide and water
Carbon
dioxide
Water
Glucose
PHOTOSYNTHESIS
Oxygen
gas
PHOTOSYNTHESIS
Plant Cells
have Green
Chloroplasts
The thylakoid
membrane of the
chloroplast is
impregnated with
photosynthetic
pigments (i.e.,
chlorophylls,
carotenoids).
• The location and structure of chloroplasts
Chloroplast
LEAF CROSS SECTION
MESOPHYLL CELL
LEAF
Mesophyll
Stomata
CHLOROPLAST
Intermembrane space
Outer
membrane
Granum
Grana
Stroma
Inner
membrane
Stroma
Thylakoid
Thylakoid
compartment
Chloroplasts: Sites of Photosynthesis
• Photosynthesis
– Occurs in chloroplasts - organelles
– All green plant parts have chloroplasts and carry
out photosynthesis
• The leaves have the most chloroplasts, therefore is
the site of most photosynthesis
• The green color comes from chlorophyll (pigment) in
the chloroplasts (organelle)
• The pigments purpose is to absorb light energy
Photosynthesis occurs in chloroplasts
• A chloroplast contains:
– stroma, a fluid
– grana, stacks of thylakoids
• The thylakoids contain chlorophyll
– Chlorophyll is the green pigment that captures
light for photosynthesis
Draw and Label the parts of the
Chloroplast!
THE COLOR OF LIGHT SEEN IS THE
COLOR NOT ABSORBED
• Chloroplasts
absorb light
energy and
convert it to
chemical energy
Light
Reflected
light
Transmitted
light
Chloroplast
Absorbed
light
WHY ARE PLANTS GREEN?
It's not that easy bein' green
Having to spend each day the color of the leaves
When I think it could be nicer being red or yellow or gold
Or something much more colorful like that…
Kermit the Frog
Electromagnetic Spectrum and
Visible Light
Gamma
rays
X-rays
UV
Infrared &
Microwaves
Visible light
Wavelength (nm)
Radio waves
WHY ARE PLANTS GREEN?
Different wavelengths of visible light are seen by
the human eye as different colors.
Gamma
rays
X-rays
UV
Infrared
Visible light
Wavelength (nm)
Microwaves
Radio
waves
The feathers of male cardinals
are loaded with carotenoid
pigments. These pigments
absorb some wavelengths of
light and reflect others.
Sunlight minus absorbed
wavelengths or colors
equals the apparent color
of an object.
Why are plants green?
Chloroplast Pigments
• Chloroplasts contain several pigments
– Chlorophyll a
– Chlorophyll b
– Carotenoids
Figure 7.7
Different pigments absorb light
differently
It's not that
easy bein'
green… but it
is essential for
life on earth!