Photosynthesis McCabe 2016-2017

II. Photosynthesis General Photosynthesis = energy transformation which takes raw materials: CO2, H2O, light, enzymes, and chlorophyll to produce glucose, oxygen is produced as a byproduct Synthesis = anabolic reaction Endergonic = where light is the E input Chemosynthesis = found in some bacteria to produce sugars, but it uses chemicals for the E input Organisms that undergo photosynthesis = plants, algae, some bacteria

II. Photosynthesis B. Leaves 1. Broad, thin plant organ where photosynthesis takes place

II. Photosynthesis C. Chloroplast 1. Special membranous organelle where PS takes place

II. Photosynthesis D. Pigments 1. Specialized substances that absorb light 2. Light part of electromagnetic spectrum a. E from sun, divided into 2 parts b. measured in wavelength ( ) c. longest waves are radio waves, shortest are gamma waves 3. Visible spectrum = portion of the EM spectrum we can see a. runs from 380 nm to 750 nm b. colors: (750 nm) R O Y G B I V (380 nm)

II. Photosynthesis D. Pigments 4. Pigments have wavelengths that they absorb & reflect a. chlorophyll = green pigment that absorbs all wavelengths of the visible spectrum except green light which it reflects i. Chlorophyll a = THE MOST IMPORTANT ii. Chlorophyll b = helps chlorophyll A b. accessory pigments = absorb light E at different wavelengths & gives all that E to chlorophyll A i. Carotenes – orange ii. Xenthophylls – yellow iii. Phyobillins – red 5. CO2 & H2O a. CO2 enters leaf thru openings = stomata b. H2O enters plant thru roots

II. Photosynthesis E. PS – The Reactions *The process occurs in two phases 1. light-dependent reactions 2. light-independent reactions (Calvin Cycle, dark reactions)

II. Photosynthesis E. PS – The Reactions Light-Dependent Reactions A. occur in membranes of the thylakoid B. uses light, water, enzymes, chlorophyll C. produces ATP, NADPH2, O2 (does this in 2 photosystems) D. the purpose of the LIGHT REACTIONS is to produce E needed by the light-independent rxns

II. Photosynthesis E. PS – The Reactions 2. Light-Independent Reactions (Calvin Cycle, Dark Rxns) A. occurs in the stroma of the chloroplast B. begins and ends with a 5-carbon compound called RuBP – ribulose biphosphate C. uses CO2, enzymes, 9 ATP, 6 NADPH2 D. produces glucose E. regenerates: ADP, NADP to cycle back to the light-dependent rxns ** Think of NADP as a babysitter for the H2 which are like wild frat boys ** NADP is an electron carrier because the electrons are so high energy that they will not go where needed unless taken by a carrier