PAPER CHROMATOGRAPHY SEPARATES PLANT PIGMENTS
1) Prepare an extract of plant tissue (e.g., leaves, flowers).
2) Apply the technique of paper chromatography as a method for separating individual plant pigments contained in plant tissue extracts containing pigment blends.
2) Describe the application of this technique to the study of plant pigments and develop related testable questions.
3) Generate ideas about ways to improve the technique to yield better results.
INTRODUCTION TO PLANT PIGMENTS
A "pigment" is simply a molecule that absorbs and reflects light. Recall that white light actually consists of many colors – you may have learned “ROY G BIV” in high school physics as a way to remember the colors of light that make up the white light of the “visible spectrum”. Different pigments appear different colors because they have differing abilities to absorb and reflect various colors of light. (A more thorough discussion of the light-absorbing properties of pigments will be presented in the Spectrophotometry lab.) The broad array of colors found in plant tissues such as leaves, flowers, and fruits, can be accounted for by the presence of literally thousands of different kinds of plant pigments.
Through plant breeding and horticultural practices, humans have manipulated plants’ pigment producing capabilities to serve our own desires. News was made recently when a true blue rose cultivar was successfully created in Japan. In nature, color is an important attribute of plants that serves to attract pollinators to receptive flowers and signal fruit ripeness to seed dispersers. In some instances, colors may also serve to warn potential predators of poisonous or toxic substances contained in plant tissues.
Color-producing pigments have other important roles in plants beyond regulating interactions with animals. Chlorophyll is a pigment that reflects green light, but absorbs red and blue wavelengths and is critical for the light...