pyrenoid


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pyrenoid:

see chloroplastchloroplast
, a complex, discrete green structure, or organelle, contained in the cytoplasm of plant cells. Chloroplasts are reponsible for the green color of almost all plants and are lacking only in plants that do not make their own food, such as fungi and nongreen parasitic
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Pyrenoid

 

a cell organelle of many algae and of Hepaticae (mosses) of the order Anthocerotales. Pyrenoids, which are rounded or angular in outline, are located in or on the chloroplast. They are always closely associated with the chloroplast and serve as the site of starch formation. The size and number of pyrenoids may change with the age of the cell. The pyrenoid consists of a central protein body—the stroma—and a starchy covering (some pyrenoids lack this covering). The stroma of the pyrenoid, like that of the chloroplast, is finely granular; however, its consistency is more solid. It has embedded lamellae consisting of a continuation of more or less reduced lamellar system of the chloroplast. New pyrenoids arise as new formations or as a result of binary fission or fragmentation. The presence or absence of pyrenoids is a taxonomic characteristic.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

pyrenoid

[′pir·ə‚nȯid]
(botany)
A colorless body found within the chromatophore of certain algae; a center for starch formation and storage.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Valve shape elliptic to panduriform; striae punctate, have alveola; plastids two, pyrenoids single in each; raphe straight, with visible, thick longitudinal canals on either side Diploneis elliptica (Kutzing) Cleve (1891), Fig.9
The material was analysed and photographed in a ZEISS EM 900 at 80kV Taxonomic identification was based on morphological characteristics such as cell shape and size; number, colour, and shape of chloroplasts; presence of mucocysts; and ultrastructure of chloroplasts and pyrenoids, according to Hara and Chihara (1987).
Chloroplasts reticulate, with numerous pyrenoids. It is attached to the substrate by a stolon with rhizoids with finger-shaped extremities (specialized hapteroid cells) oriented horizontally, pale or lightly colored.
New ultrastructural aspects of pyrenoids of the lichen photobiont Trebouxia (Microthamniales, Chlorophyta).