Transcript Photosynthesis

PHOTOSYNTHESIS
Energy is used to make:
-Proteins
-Sugars
-Fats
-Nucleic acids
All living things need energy.
Energy comes from sun.
PHOTOSYNTHESIS
Energy is harnessed:
Producers (plants) are able to convert this light energy
(sunlight) into chemical energy (sugar).
PHOTOSYNTHESIS
EQUATION:
6 CO2
Carbon
Dioxide
+ 12 H2O Sunlight
Water
chlorophyll
C6H12O6 + 6 O2 + 6 H2O
Sugar
Oxygen
Water
CHLOROPLASTS
All cells in leaves
have thousands of
green organelles
called chloroplasts.
CHLOROPLASTS
Stroma:Stacks
Thylakoid:
Grana:
Cytoplasm
Flattened
of thylakoids
ofsacs;
chloroplast;
convert contains
light NRG
enzymes
to
for
chemical
making
sugar
NRG
CHLOROPHYLL
Molecule that
absorbs sunlight
energy.
Photoreactive core
SUNLIGHT
What do
Plants
appear
you think
to bewould
greenhappen
because
if chlorophyll
you placed adoes
plant
not
in
absorb
just
green
green
light?
wavelengths of light.
Just blue light?
HOW DOES A CHLOROPLAST
WORK?
A. Light reaction
1. Sunlight is absorbed by chlorophyll in thylakoid.
2. This energy is used to split water.
2 H2O
O2 + 4 H+ + 4 electrons
3. Oxygen is produced.
4. Electrons are excited (contain super energy).
5. No carbon dioxide is used; no sugar is produced.
HOW DOES A CHLOROPLAST WORK?
Light reactions harness sunlight to split water, produce
oxygen, and excite an electron. Occurs in thylakoids.
HOW DOES A CHLOROPLAST
WORK?
B. Dark Reaction (Calvin Cycle)
1. Enzymes in stroma use the excited electron’s
energy to build sugar from CO2 and H+.
2. DOES NOT REQUIRE DARKNESS, BUT CAN
HAPPEN IN DARK BUT . . .
Only if there are enough excited electrons. Once those
run out – photosynthesis is done.
Leaf Structure
Cuticle – waxy
layer on top of
leaf
Leaf Structure
Epidermis –
outermost layer
of cells
Leaf Structure
Upper
epidermis
Lower
epidermis
PALISADES
Leaf Structure
Palisade layer –
“tall” cells;
primary site of
photosynthesis
in leaf (many
chloroplasts)
Leaf Structure
Spongy layer –
cells are not
tightly packed;
room for gas
exchange; some
chloroplasts
Leaf Structure
Guard cells –
form openings
to allow gases
and water to
enter/leave
leaf; some
chloroplasts
Leaf Structure
Stomata –
openings
formed by
guard cells
Leaf Structure
Xylem –
transport of
water
Leaf Structure
Phloem –
transport of
sugar