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Definition: CHLOROPHYLL from A Dictionary of Entomology

Noun. (Greek, chloros = yellow + phyllon = leaf. PL, Chlorophylls.) Green colouring matter of plants and one substance found in blood of insects. Variants include: chlorophyll a (blue-green chlorophyll) and chlorophyll b (yellow-green chlorophyll).


Summary Article: Chlorophyll
from Encyclopedia of Environment and Society

CHLOROPHYLLS ARE A class of chemical pigments found in many types of plant life, and are necessary for the process of photosynthesis. Chlorophylls absorb light in particular parts of the electromagnetic spectrum, meaning that they have a very vivid green color, which is characteristic of their presence and encourages industrial applications as well as health promotion.

Photosynthesis is the process by which sunlight is converted into chemical energy within plant cells through organic carbon compounds. It is possible that chlorophyll or a similar substance was a vital link in the evolution of life. The 1997 Pathfinder mission to mars found some evidence that substances similar to chlorophyll might be present in Martian soil.

The five types of chlorophyll (a, b, c, d, and e) are found in the higher plants and different forms of algae; bacterio-chlorophyll is found in some types of bacteria. Chlorophylls consist of a magnesium atom surrounded by a porphyrin ring containing nitrogen and with a carbon-hydrogen chain also attached. This structure is quite similar to that of hemoglobin, which is the vital substance within blood that transports oxygen. Since chlorophyll tends to hide other colors present within plants and especially their leaves, it is when light is reduced that other colors emerge, such as during autumn, when the leaves of many deciduous trees change from green to red, yellow, or brown. The use of chlorophyll fluorescence has become a tool of considerable importance for plant physiologists and ecophysiologists, who are able to use the various techniques involved in diagnosing not just the rate of photosynthesis, but also considerable amounts of information about the health of the plant concerned and its reactions to its environment. In particular, it is useful in measuring environmentally induced stress.

Chlorophyll-bearing vegetables have been the subject of investigation in the hope that they will inhibit the growth of some cancer cells. Spinach is indicated by some research as an important dietary item that may assist with this prophylaxis.

    SEE ALSO:
  • Carbon Dioxide; Deciduous Forest; Decomposition; Joint Forest Management.

BIBLIOGRAPHY
  • F. Galvano; A. Piva; A. Ritieni; G. Galvano, “Dietary Strategies to Counteract the Effects of Mycotoxins: A Review,” Journal of Food Protection (v.64/1, 2001).
  • Bernhard Grimm; Robert J. Porra; Wolfhart Rüdiger; Hugo Scheer, eds., Chlorophylls and Bacteriochlorophylls: Biochemistry, Biophysics, Functions and Applications (Springer, 2006).
  • Kate Maxwell; Giles N. Johnson, “Chlorophyll Fluorescence: A Practical Guide,” Journal of Experimental Biology (v.51/345, 2000).
  • John Walsh
    Shinawatra University
    Copyright © 2007 by SAGE Publications, inc.

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