a prism can be used to separate sunlight into different wavelengths of light
TRANSCRIPT
A prism can be used to separate sunlight into different wavelengths of light.
Chlorophyl a and accessory pigments (carotenoids, chlorophyll b, etc.) reflect mostly green and yellow light; other wavelengths are absorbed
and their energy is used in photosynthesis.
A very elegant experiment done in the late 1800’s:
Engelmann demonstrated that photosynthesis coincides with
specific wavelengths in the visible light spectrum.
The green filament is Spyrogyra, an alga, under a
microcope where a tiny prism was setup to split visible light
into a spectrum.
Aerobic bacteria are attracted to the oxygen produced by the
alga.
Thanksgiving Gifts from Photosynthesis
Parts of the Chloroplast
Granum =
stack of thylakoids
(stack of pancakes)
Stroma
Watery space between grana
Inner Membrane
Outer Membrane
Thylakoid = one flattened sack (one pancake)
Photosynthesis involves manyRedox Reactions
• Involve loss or gain of electrons
• Oxidation = loss of electrons (become more positive)
• Reduction = gain of electrons (become more negative)
Ex.: H2O ionizes H+ + OH-
H was oxidized, OH was reduced
Light Reaction of PhotosynthesisCO2 + H2O C6H12O6 + O2
Notice that no sugars are made in this stage,only oxygen, ATP, and NADPH.
Light Reaction Summary
1. Location:
2. Reactants Used:
3. Products/By-Products:
Thylakoid Membrane, Grana of Chloroplast
Water
Oxygen – by-product, exits plants through stomata
ATP and NADPH for the Dark Reaction
LIGHT REACTION REVIEW
1. What is the Energy source for the Light Reaction?
2. Where does the Light Reaction Occur in the Chloroplast?
3. Why do the electrons of the chloroplast become excited?
PHOTONS
IN THE THYLAKOID MEMBRANE OF THE GRANA
“ABSORB” PHOTON ENERGY, JUMP AN ENERGY LEVEL
6. What happens to the Energy level as electrons
travel from Photosystem II to Photosystem I?
4.What molecule(s) becomes oxidized?
5. What molecule(s) becomes reduced?
Chlorophyll A, Water
Chlorophyll A, Primary Electron Acceptor, NADP
It decreases; reactions are Endergonic because of photon input
Light Reaction of Photosynthesis
1. What replaces the electrons lost in Photosystem I?
2. What replaces the electrons lost in Photosystem II?
3. What is the reactant used in the Light reaction?
Electrons from Photosystem II
Electrons from the Water Molecule
The Water Molecule
4.What are the products in the Light reaction?
5.What does chemiosmosis mean?
6. What is produced in the process of chemiosmosis?
O2 , ATP and NADPH
Making ATP by the diffusion of H+ through ATP Synthase
ATP