Photosynthesis AP Biology

Photosynthesis the musical Youtube Light reactions search photosynthesis music episode1 Calvin cycle search episode 2

The Equation 6CO2 + 6H2O + light  C6H12O6 + 6O2 Chlorophyll required Water both consumed & produced

Chloroplasts Site of photosynthesis Structure Double membrane Thylakoids Granum (Stack of thylakoids) Stroma

Chloroplasts Relating structure to function Thylakoid space Allows for accumulation of H+ Segregates H+ from rest of organelle

Chloroplasts Relating structure to function Thylakoid membrane Contains photosystems & ETC

Chloroplasts Relating structure to function Large number of thylakoids Large surface area Large number of ETC and photosystems

Chloroplasts Relating structure to function Inner membrane Segregates chemical of Calvin-Benson cycle from cytosol

HOW PHOTOSYNTHESIS WORKS Go to blog and get the details transferred into your notes – then we’ll talk!

Photosynthesis

Light Reactions

Light Reactions Photosystem II captures light energy P680

Light Reactions Light energy passed to reaction center P680

Light Reactions 2 e- boosted to higher energy state P680

Light Reactions 2 e- passed through ETC to Photosystem I H+ gradient created; ATP produced ATP P700 P680

Light Reactions Photosystem I captures light energy Passes it to reaction center ATP P700 P680

Light Reactions e- from P700 boosted to higher energy state P700 P680 ATP P700 P680

Light Reactions e- move through ETC e- accepted by NADP+ NADP+ P700 ATP NADP+ P700 P680

Light Reactions 2e- + 1H+ + NADP+  NADPH ATP NADP+ NADPH P700 P680

Light Reactions Water split e- from water replace lost e- from P680 O2 leaves ATP NADPH H2O O2 P700 H+ P680

Time for music!!!

Calvin Cycle

Notes for Calvin Cycle Page

Calvin Cycle Rubisco fixes 6CO2 to 6RuBP (5-C) RuBP = ribulose biphosphate 3PG (3-C) produced 3PG = 3-phosphoglycerate

Calvin Cycle 3PG converted to 12 G3P G3P = glyceraldehyde 3-phosphate 12 ATP used 12 NADPH used

Calvin Cycle 2 G3P exit cycle & used to make glucose Glucose used to make sugars & other carbohydrates

Calvin Cycle 10 G3P (3-C) used to make 6 RuBP (5-C) 6 ATP used

Importance of Calvin Cycle G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules The hydrocarbon skeleton of G3P can form Fatty acids and glycerol to make plant oils Glucose phosphate (simple sugar) Fructose (which with glucose = sucrose) Starch and cellulose Amino acids

C4 Photosynthesis In hot, dry climates In C4 plants Stomata must close to avoid wilting CO2 decreases and O2 increases O2 starts combining with RuBP instead of CO2 Photorespiration, a problem solve in C4 plants In C4 plants Fix CO2 to PEP a C3 molecule The result is oxaloacetate, a C4 molecule In hot & dry climates Avoid photorespiration Net productivity about 2-3 times C3 plants In cool, moist, can’t compete with C3

Chloroplast distribution in C4 vs. C3 Plants

CO2 Fixation in C4 vs. C3 Plants

CAM Photosynthesis Crassulacean-Acid Metabolism CAM plants partition carbon fixation by time During the night CAM plants fix CO2 Forms C4 molecules, Stored in large vacuoles During daylight NADPH and ATP are available Stomata closed for water conservation C4 molecules release CO2 to Calvin cycle

CO2 Fixation in a CAM Plant

Climatic Adaptation: Photosynthesis Each method of photosynthesis has advantages and disadvantages Depends on the climate C4 plants most adapted to: high light intensities high temperatures Limited rainfall C3 plants better adapted to Cold (below 25C) High moisture CAM plants better adapted to extreme aridity CAM occurs in 23 families of flowering plants Also found among nonflowering plants

Review Flowering Plants Photosynthetic Pigments Photosynthesis Light Reactions Noncyclic Cyclic Carbon Fixation Calvin Cycle Reactions C4 CAM