A prism can be used to separate sunlight into different wavelengths of light.

In eukaryotes, photosynthesis happens in the chloroplast.

What is the picture telling us?

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

Have a great Thanksgiving holiday!

Photosynthesis & Cell Respiration CO 2 + H 2 O ↔ C 6 H 12 O 6 + O 2

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 many Redox Reactions Involve loss or gain of electrons Oxidation = loss of electrons (become more positive) Reduction = gain of electrons (become more negative) Ex.: H 2 O ionizes  H + + OH - H was oxidized, OH was reduced

Photosynthesis – Light Reactions

Notice that no sugars are made in this stage, only oxygen, ATP, and NADPH.

Light Reaction of Photosynthesis CO 2 + H 2 O C 6 H 12 O 6 + O 2 Notice that no sugars are made in this stage, only oxygen, ATP, and NADPH.

H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+

Now with Enzymes! (add details)

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? O 2, ATP and NADPH Making ATP by the diffusion of H + through ATP Synthase ATP