Transcript Notes Photosynthesis

Photosynthesis
Mrs. MacWilliams
Academic Biology
I. Two ways to get food
A.
1.
“troph” = Food/feeder
Autotrophs
a.
b.
Auto = self
Autotrophs make their own food

2.
PLANTS
Heterotrophs
a.
b.
Hetero = different
Heterotrophs get their food differently (they have to
eat it)

ANIMALS, FUNGUS
II. Gas Exchange
A.
Plants
1. Leaves take in CO2 and give off O2
2. When plants use food they make, the cells
respire, taking in O2 and giving off CO2
3. Plant leaves allow gas exchange through an
opening called the stomata
III. Photosynthesis
A. Converts the sun’s energy into chemical
energy stored in sugar
B. Takes place in chloroplasts
1. Chlorophyll- pigment that absorbs sunlight
C. Chloroplasts
1.
2.
3.
Have photosynthetic membranes called
thylakoids that are arranged in stacks
Chlorophyll in located in the thylakoid
Chlorophyll absorbs light and the energy from
light is transferred to electrons
a.
4.
BECOME HIGH ENERGY ELECTRONS!
Stroma = fluid outside of the thylakoid
CHLOROPLAST DIAGRAM
D. High-Energy Electrons
1.
2.
3.
electron carrier- compound that accepts a pair of highenergy electrons and transfers them to another
molecule.
Plants use electron carriers to transport high-energy
electrons from chlorophyll to other molecules.
Electron carriers: NADH and NADPH
Think of a high-energy electron as being similar to a hot
potato. If you wanted to move the potato from one place
to another, you would use an oven mitt—a carrier—to
transport it.
E. Photosynthesis Reaction

6CO2 + 6 H2O + light energy → C6H12O6 + 6O2

The food plants make is called glucose (sugar)
F. 2 Different Reactions
1. Light Dependent Reactions
 Capture light energy for photosynthesis
 Use sunlight to make ATP and NADPH
 In thylakoid membranes of chloroplast
 H2O is a substrate provides electrons and hydrogen ions
 O2 is a product of this reaction
2. Light Independent (Calvin Cycle)



Happens in the stroma
Light is NOT needed
ATP and NADPH (from light-dep. rxn) are used to produce
glucose from CO2
Amoeba Sisters: Photosynthesis