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

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 O2 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

H2O

NADP+ NADPH

e–

ATP

ATP SYNTHASE

PHOTOSYSTEM IPHOTOSYSTEM II ADP + Pi

e–

first electron transport system

STROMA

Fig. 7.12a, p. 121

http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf

DPIP!

Light Independent Rxns: Stroma

Light Dependent Rxns: Thylakoid Membrane

Sun = Energy Source

Chlorophyll absorbs solar energy

H2O = reactant

O2 waste

NADPH

ATP

CO2 reactant

CO

O

C

OO

NADPH drops off HH H

HH

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

H2O

NADP+ NADPH

e–

ATP

ATP SYNTHASE

PHOTOSYSTEM IPHOTOSYSTEM II ADP + Pi

e–

first electron transport system

STROMA

Fig. 7.12a, p. 121

http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf

DPIP!

Light Independent Rxns: Stroma

Light Dependent Rxns: Thylakoid Membrane

Sun = Energy Source

Chlorophyll absorbs solar energy

H2O = reactant

O2 waste

NADPH

ATP

CO2 reactant

CO

O

C

OO

NADPH drops off HH H

HH

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!