By Levi Clancy for Student Reader on
Chlorophyll (Chl) consists of a porphyrin ring with a central magnesium (Mg) atom. It reflects green light, and must be embedded in a membrane to function. Eukaryotes store chlorophyll in the chloroplast. Chloroplasts have 3 membranes and 3 compartments, with thylakoids stacked like pancaked forming grana and stroma. Prokaryotes have chlorophyll in chlorosomes, cytoplasmic membrane or invaginations of the cellular membrane. All photosynthetic organisms have chlorophyll a. Accessory pigments (chlb, xanthophylls, carotenoids) absorb energy that chlorophyll a does not absorb. Pigment diversity expands range of usable hv. Calvin mapped path of carbon in photosynthesis using carbon-14, ion exchange, paper chromatography & radioautography. Shorter wavelengths with more energy do not penetrate below 5 meters in sea water. That is why there is an advantage to absorbing longer wavelengths. To find absorbance spectrum, create photosynthetic cell culture, extract Chl and then measure absorbances.