Photosynthesis SUMMARY EQUATION 6 CO 2 12 H
![Problem: Photorespiration If [O 2] > [CO 2] in leaves Rubisco fixes O 2](https://slidetodoc.com/presentation_image_h2/31defa26b66fea15215cf6343e407e1a/image-11.jpg "Problem: Photorespiration If [O 2] > [CO 2] in leaves Rubisco fixes O 2")
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Photosynthesis
SUMMARY EQUATION 6 CO 2 + 12 H 2 O + light C 6 H 12 O 6 + 6 O 2 + 6 H 2 O 6 CO 2 + 6 H 2 O + light C 6 H 12 O 6 + 6 O 2 CO 2 + H 2 O + light CH 2 O + O 2 (emphasizes production of glucose 1 carbon at a time)
SITE OF PHOTOSYNTHESIS -- PLANTS
SITE OF PHOTOSYNTHESIS – PROKARYOTES • Lack chloroplasts • Chlorophyll built into plasma membrane
Structure of Chloroplasts
Light CO 2 Overview of photosynthesis ADP +P Light Rxns (thylakoids) ATP NADP+ Calvin Cycle (stroma) NADPH H 2 O O 2 Light Rxns • Take e- from H 2 O • Use light energy to boost e- to higher energy level • Use some energy to make ATP • Add high energy eto NADP+ CH 2 O Calvin Cycle • AKA Dark Rxn • Uses ATP produced in light rxn • Takes high energy efrom NADPH and adds them to CO 2 • Produces sugar 1 carbon at a time
LIGHT REACTIONS – CYCLIC ELECTRON FLOW-PHOTOSYSTEM I • Photosystem I • Few 100 pigment molecules (chlorophyll a, b, & carotenoids) • Reaction center • Chlorophyll a molecule • Bound to specific proteins • Closer to 1 o electron acceptor • Antenna pigments absorb photons and pass to rxn center
LIGHT REACTIONS – NONCYCLIC ELECTRON FLOWPHOTOSYSTEM II & I P 680 photosystem II
Calvin Cycle Vocabulary (just know abbreviations) • • • Ru. BP = ribulose biphosphate Rubisco = Ru. BP carboxylase PGA = phosphoglycerate DPGA = diphosphoglycerate G 3 P= glyceraldehyde phosphate Ru. P = ribulose phosphate
Calvin Cycle. Light Independent Reaction Locationstroma 5 G 3 P 6 G 3 P 1 G 3 P 2 G 3 P
Problem: Photorespiration If [O 2] > [CO 2] in leaves Rubisco fixes O 2 instead of CO 2 5 -C compound produced 5 -C 1 PGA enters Calvin Cycle 1 glycolate (2 -C) exits chloroplasts and enters peroxisomes • Decreases productivity • Fostered by hot, dry, bright days • • •
C 4 Plants • Fix CO 2 as 4 C compound • Segregate CO 2 fixation from Calvin cycle • Acts as CO 2 pump • PEP carboxylase has lower affinity for O 2 than rubisco • Adaptation in hot regions with intense light
CAM PLANTS Crassulacean Acid Metabolism