Name some common producers › Plants, algae, some protists, cyanobacteria Define photoautotroph › An organism that uses light energy to produce food Define chemoautotroph › An organism that uses chemical energy to produce food
Fig (a) Plants (c) Unicellular protist 10 µm 1.5 µm 40 µm (d) Cyanobacteria (e) Purple sulfur bacteria (b) Multicellular alga
State the organelle of photosynthesis › Chloroplast Where are chloroplasts concentrated in plants? › The green tissue on the interior of the leaf › Mesolphyll
Fig. 10-3a 5 µm Mesophyll cell Stomata CO 2 O2O2 Chloroplast Mesophyll Vein Leaf cross section
Explain how gases are exchanged between the plant and the environment. › Stoma are openings in the epidermis of leaves › Guard cells surround the stoma and they regulate the opening & closing of the stoma › When open, CO 2 can enter while O 2 and H 2 O can exit
Fig. 10-3b 1 µm Thylakoid Space (lumen) Chloroplast Granum Intermembrane space Inner membrane Outer membrane Stroma Thylakoid Structure of the chloroplast Thylakoid is site of light reactions Stroma is site of Calvin Cycle
1950’s – scientists used heavy isotope of oxygen ( 18 O) to follow oxygen through photosynthesis. Tagged oxygen of CO 2 and found no tagged O 2 given off Tagged O 2 of H 2 O and found tagged O 2 given off
Reactants: Fig CO 2 Products: 12 H 2 O 6 O 2 6 H 2 O C 6 H 12 O 6
Equation › 6CO 2 + 6H 2 O Light C 6 H 12 O 6 + 6O 2 Redox reaction of photosynthesis › Oxidized: H 2 O to O 2 › Reduced: CO 2 to C 6 H 12 O 6
Photosynthesis consists of the light reactions (photo – absorbs light energy) and the Calvin cycle (synthesis – makes sugar)
Light Reactions Calvin Cycle Takes place in the thylakoids Split H 2 O Release O 2 Reduce NADP+ to NADPH Produce ATP via photophosphorylation Takes place in the stroma Forms sugar using › CO 2 from atmosphere › ATP and NADPH from light reactions Starts with carbon fixation
Light Fig H2OH2O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O2O2 Calvin Cycle CO 2 [CH 2 O] (sugar)