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Algal Pigments

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Katie Kyler BIO 4415 Winter 2003 Algal Pigments Introduction All photosynthesizing plants have certain pigments in them by which they capture sunlight. All plants have in common the photosynthetic pigment of chlorophyll, but the other accessory pigments as different. These accessory pigments can be the same between two red algae, or two green algae. In this lab a red, green and brown algae will be used to extract the photosynthetic pigments from. We will also be extracting the photosynthetic pigments from Coleus sp., which is a red land plant leaf and, and compare the accessory pigments of this to the red algae. Methods and Materials We used two different kinds of red algae for this experiment. The first was Polysiphonia sp. and the second Porphyra sp. The green algae were Entreromorpha linza, and the brown algae were Fucus gardneri. The test plant we used to compare against the red algae was Coleus sp. A different procedure was conducted for extracting pigments from the different colors of algae. The red algae were grinded using both water and 90% acetone in order to get all the pigments out. ...read more.


When chlorophyll a is present, peaks should appear on a spectophotometric reading at 430nm and 663nm. Therefore all the species used below should have peaks at approximately 430nm and 663nm. This should only be the case when using a lipophilic extracting agent such as 90% acetone or DMSO because the chlorophyll a is hydrophobic itself. Porphyra needed to be crushed using both water and acetone because there are pigments in Porphyra which are hydrophobic, and hydrophilic. Therefore the water would remove the hydrophilic pigments, and the 90% acetone would extract the hydrophobic pigments. When looking at the wavelengths present in the spectrometer reading (see graph 1) we see that the hydrophilic pigments of Phycoerythrin (565, 500nm) and Phycocyanin (620 nm) are present. There was also a peak at 436nm which is most likely a little chlorophyll a that was extracted as well. A seen on graph 2, Porphyra in 90% acetone extracted chlorophyll a with peaks at 434nm and 664nm. However, we did not see peaks that represent the presence of chlorophyll d which is present in red algae. ...read more.


and chlorophyll c (466nm, 584nm, 620nm). The peaks that represent these two pigments are labeled on graph 5. Two of the peaks for chlorophyll c are quite slight, but could still be valid readings. When we tested our hypothesis species was Coleus sp. it was postulated that it would have the same accessory pigments as the red algae because Coleus was also red in color. However the results we got from the spectrometer readings were quite different. When pigments were extracted from Coleus using water (see graph 6) a trace of chlorophyll a was found at 436nm and a bunch of other peaks appeared that did not show up in Porphyra in water (see graph 1). The peaks present in Coleus in water may be other accessory pigments that have different wavelength than what we have covered. The Coleus in acetone did show peaks at chlorophyll a (434nm and 664nm) as well as a peak at 462nm which is most likely a carotinoid pigment of some type. In conclusion, the test plant, Coleus sp. did not appear to have the same accessory pigments as our red algae species of Porphyra sp. Even though the plants appeared to be the same color externally, their photosynthetic pigments are not the same. ...read more.

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