Photosynthesis

What is the ultimate source of all energy

How does the energy get from the sun into the foods we eat? energy

Why do we see colors? The sun sends downs little packets of light energy called: The sun sends downs little packets of light energy called: PHOTONS PHOTONS

Why do we see colors? Photons group together in waves Photons group together in waves The waves have different lengths The waves have different lengths Each “wavelength” presents itself as a color Each “wavelength” presents itself as a color Photons Wavelengths

Why do we see colors? Plants reflect this color of light. That’s why most plants are GREEN Plant pigments like chlorophyll absorb these colors of light so these colors are not seen. What colors of light would a plant with purple leaves absorb?

What colors are being absorbed and what colors are being reflected? Photos courtesy of flowerpictures.net and picturesof.net

Why do we see colors? What do we call the compounds that absorb and reflect wavelengths of light? What do we call the compounds that absorb and reflect wavelengths of light? Which compound reflects the green wavelengths thereby making plants green? Which compound reflects the green wavelengths thereby making plants green? Where would we find this compound? Where would we find this compound?

Chloroplast structure Disks called GRANA contain the pigment CHLOROPHYLL. The liquid portion of a chloroplast is the STROMA

Where do we find chloroplasts?

stoma Chloroplast containing chlorophyll Chloroplasts are found in cells of leaves.

Review 1. What is the ultimate source of all energy? 2. In what form does light energy come to the earth? 3. What compounds absorbs wavelengths? 4. How do we see colors? 5. Where in a leaf do we find pigments?

What process captures the light energy and uses it to make food?

OVERVIEW OF PHOTOSYNTHESIS PLANTS TAKE IN CO 2 AND H 2 O PLANTS MAKE GLUCOSE AND OXYGEN SUNLIGHT PROVIDES THE ENERGY FOR PHOTOSYNTHESIS

Photosynthesis What is photosynthesis? What is photosynthesis? Photosynthesis is the process by which: Photosynthesis is the process by which: water carbon dioxide oxygen glucose TAKE INAND USINGMAKE PLANTS (producers) light chlorophyll

Photosynthesis 2 steps: 2 steps:  Light reactions  Dark reactions (aka Calvin cycle) Light ReactionDark Reaction

Who was Calvin anyway? A member of the faculty at UC Berkeley since 1937, Melvin Calvin received the 1961 Nobel prize in chemistry for identifying the path of carbon in photosynthesis. A member of the faculty at UC Berkeley since 1937, Melvin Calvin received the 1961 Nobel prize in chemistry for identifying the path of carbon in photosynthesis. The cycle of reactions in the dark phase of photosynthesis was named after him for his work in identifying the processes taking place.

Photosynthesis Light reaction: Light reaction:  Occurs in the grana  Must have light light Light Reaction Dark Reaction LIGHT REACTION Dark Reaction grana (chlorophyll)

Photosynthesis Dark reactions (aka Calvin cycle) : Dark reactions (aka Calvin cycle) :  Occurs in the stroma  Occurs in the light and dark Light Reaction Dark Reaction Light Reaction DARK REACTION stroma (liquid)

Step 1: Light Reactions H2OH2O O2O2 O2O2 O2O2 O2O2 O2O2 HH How does the O 2 leave the leaf? ENERGY light energy reacts with the chlorophyll water is split by the light energy H is kept for the dark reaction O 2 is released OH2OH2

Step 2: Dark Reactions AKA: CALVIN CYCLE AKA: CALVIN CYCLE CO 2 H C 6 H 12 O 6 How does CO 2 enter the plant? H from the water split in the light reaction is present CO 2 enters the chloroplast the reactants H and CO 2 combine H H + CO 2 glucose is the product Other carbohydrates besides glucose may be made in photosynthesis

Photosynthesis Review Light reactions: H 2 O split into H 2 + O Dark reactions: H + CO 2 = C 6 H 12 O 6 H2OH2O Light ReactionDark Reaction CO 2 C 6 H 12 O 6 O2O2 chlorophyll

Photosynthesis Formula How would this be written as a chemical equation? What goes in? (the reactants) What comes out? (the products) H2OH2O Light Reaction Dark Reaction CO 2 C 6 H 12 O 6 O2O2 chlorophyll H2OH2OCO 2 C 6 H 12 O 6 O2O2

Photosynthesis Formula What’s wrong with this equation? The number of atoms is not equal on both sides of the equation. Balance the equation so that the number of atoms of each element is equal on both sides. H2OH2OCO 2 C 6 H 12 O 6 O2O2 one carbon atom reactant 6 carbon atoms product 6 66(1) Now balance it as if TWO glucose molecules were being produced.

Photosynthesis Review What goes in? (the reactants) What comes out? (the products) H2OH2O Light Reaction Dark Reaction CO 2 C 6 H 12 O 6 O2O2 chlorophyll 6CO 2 + 6H 2 O 6O 2 + C 6 H 12 O 6 light chlorophyll