AP Lab 4: Plant Pigments and Photosynthesis Prelab Discussion!

 What is chromatography? –A separation technique that separates molecules by size and solubility AP Lab 4 Part A: Pigment Chromatography

 What will our setup look like? We will substitute a screw-top jar for a graduated cylinder!

Part A: Chromatography  Remember to make a dark pigment line!  Allow pigment to dry between applications.  Do not allow solvent above pigment line at start! Be sure to mark solvent line at end for calculations! solvent

AP Lab 4 Part A: Pigment Chromatography  What is Rf and how do you calculate it? –It is the relationship between the distance moved by a pigment and the distance moved by the solvent.

AP Lab 4 Part B: Photosynthesis  How could one measure photosynthetic rates? –Amount of O 2 produced –Amount of glucose produced –Amount of ATP produced –Amount of NADPH created by the reduction reaction:  NADP + + H +  NADPH

AP Lab 4 Part B: Photosynthesis  We will focus on the NADPH production.  We know that NADPH is the final electron and H receptor in the light dependent reactions.  We will be substituting the compound DPIP (a blue dye to be the final electron acceptor.  Therefore as photosynthesis progresses, the blue dye will become increasingly clear.

Light Dependent Reactions: sunlight photolysis THYLAKOID COMPARTMENT second electron transport system H2OH2O NADP + NADPH e–e– ATP ATP SYNTHASE PHOTOSYSTEM IPHOTOSYSTEM II ADP + P i e–e– first electron transport system STROMA Fig. 7.12a, p DPIP!

Light Independent Rxns: Stroma Light Dependent Rxns: Thylakoid Membrane Sun = Energy Source Chlorophyll absorbs solar energy H 2 O = reactant O 2 waste NADPH ATP CO 2 reactant C O O C O O NADPH drops off H HH H H Glucose made with ATP energy NADP+

AP Lab 4 Part B: Photosynthesis  We will measure the % absorbance with probeware and a colorimeter. –What would a high % absorbance mean reagrding photosynthetic rate? –A low % absorbance?

AP Lab 4: Plant Pigments and Photosynthesis AP Lab 4 Day 2: Take out your flowcharts and lab packets.

Light Dependent Reactions: sunlight photolysis THYLAKOID COMPARTMENT second electron transport system H2OH2O NADP + NADPH e–e– ATP ATP SYNTHASE PHOTOSYSTEM IPHOTOSYSTEM II ADP + P i e–e– first electron transport system STROMA Fig. 7.12a, p DPIP!

Light Independent Rxns: Stroma Light Dependent Rxns: Thylakoid Membrane Sun = Energy Source Chlorophyll absorbs solar energy H 2 O = reactant O 2 waste NADPH ATP CO 2 reactant C O O C O O NADPH drops off H HH H H Glucose made with ATP energy NADP+

Part B: Photosynthesis  Note setup!

Part B: Photosynthesis  Troubleshooting Tips: –Calibrate once!  Two people can calibrate the sensor then help out with the cuvette setup! –Remember to mix each cuvette prior to taking an absorbance reading! –Remember to handle cuvettes by the curved sides and load properly!