Pigments Seen
There are three major types of photosynthetic pigments commonly found in leaves: chlorophylls (green) and two types of yellow accessory pigments, carotenoids and xanthophylls.
Flowering plants have two types of chlorophyll: a and b. These are similar but have slightly different structures and absorption optima. Our chromatography results verify this difference in structure and light absorbance, as chlorophyll a migrated further and reflected more blue-green colored wavelengths, while chlorophyll b didn't migrate as quickly and appeared more yellow-green in color.
Carotenoids are pure hydrocarbons, while xanthophylls have some oxygen atoms in their makeup. This means that carotenoids are nonpolar (like our chromatography solvent) while xanthophylls are more likely to have charged areas around their oxygen-containing regions. This was demonstrated on our chromatography strip, as beta carotene formed a band almost at the solvent front (so its Rf would be about 1) while three different types of xanthophylls formed bands closer to the original starting point on the strip, and one faint band didn't even migrate from the starting point.
Pheophytin is a grayish pigment resulting from the partial breakdown of chlorophyll, and appeared in small amounts near the solvent front on the chromatography strip. |
