| MadSci Network: General Biology |
Hi Cathy!! Chlorella is a single-celled green algae, which belongs to the phylum Chlorophyta. It is spherical in shape, about 2 to 10 μm in diameter, and is without flagella. Chlorella contains the green photosynthetic pigments chlorophyll-a and -b in its chloroplast To measure the OD of Chlorella using spectrophotometer you need to measure chlorophyll a and chlorophyll b since there are the main chlorophyll pigments in Chlorella Take absorbance measurements of the whole ethanol extract (i hope you will extract the pigments from Chlorella using ethanol, at the following wavelengths, using absolute ethanol as the blank for zeroing the machine. 663 nm, 645 nm and 750 (measure of turbidity). Make sure that 750 readings are zero...if not subtract this reading from 664, 647 and 630 and use those values in the below given equations.. Jeffrey and Humphrey's Trichromatic Equations (1975) Chlorophyll a: 11.85 X (Abs 664) - 1.54 X (Abs 647) - 0.08 X (Abs 630) Chlorophyll c: 24.52 X (Abs 630) - 7.60 X (Abs 647) - 1.67 X (Abs 664) Lorenzen's (1967) Pheopigment-corrected Chlorophyll a Chlorophyll a: 26.7 X (Abs 664b - Abs 665a) Abs664b: Abs750 – Abs664 before adding 0.1N HCl to the sample Abs665a: Abs750 – Abs 665 after adding 0.1N HCl to the sample Abs 750, Abs664, Abs647, Abs665 and Abs630 are the absorbance read by spectrophotometer Best of luck shashank References: http://en.wikipedia.org/wiki/Chlorella Jeffrey, S.W., G. F. Humphrey. 1975. New spectrophotometric equations for deter- -mining chlorophylls a, b, c, and c2 in higher plants, algae and natural phyto- plankton. Biochem. Physiol. Pflanz., 167: 191-194. Lorenzen, C. J. 1967. Determination of chlorophyll and phaeo-pigments: Spectrophoto- metric equations. Limnol. Oceanogr., 12:343-346
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