Canadian Medical Guide > Organisms > Algae Terms and Definitions




Algae

Medical Definition: A major group of polyphyletic organisms of extremely varied morphology and physiology, mostly photosynthetic, but distinguished from plants by their complex form of sexual reproduction. They are freshwater and marine, terrestrial and subterranean; some are neustonic (living at the interface of water and the atmosphere). They live in various protozoa and within other plants. They live also in soil and on soil surfaces, on long-persistent snows, and in Antarctic rocks. Thermophilic algae inhabit hot springs. (From Webster, 3d ed; from Bold & Wynne, Introduction to the Algae, 2d ed, pp1-6)
Guide Notes: GEN or unspecified; prefer specifics
Algae Categories.
Canadian Medical Guide Definition Algae, Brown - Predominantly marine algae of the division Phaeophyta, having CHROMATOPHORES containing carotenoid pigments. ALGINATES and phlorotannins occur widely in all major orders. They are considered the most highly evolved algae because of their well-developed multicelluar organization and structural complexity.
Canadian Medical Guide Definition Algae, Golden-Brown - Microscopic fresh water algae in the family Chrysophyceae. They share many features with the BROWN ALGAE but are planktonic rather than benthic. Though most are photosynthetic, they are not considered truly autotrophic since they can become facultatively heterotrophic in the absence of adequate light. In this state they can feed on BACTERIA or DIATOMS.
Canadian Medical Guide Definition Algae, Green - Algae of the division Chlorophyta, in which the green pigment of CHLOROPHYLL is not masked by other pigments. Green algae have over 7000 species and live in a variety of primarily aquatic habitats. Only about ten percent are marine species, most live in freshwater. They are more closely related to the green vascular land PLANTS than any other group of algae.
Canadian Medical Guide Definition Algae, Red - Algae of the division Rhodophyta, in which the red pigment (PHYCOERYTHRIN) predominates. However if this pigment is destroyed, the algae can appear purple, brown, green, or yellow. Two important substances found in the cell walls of red algae are AGAR and CARRAGEENAN. Red algae are thought to be closely related to the prokaryotic CYANOBACTERIA.
Canadian Medical Guide Definition Characeae - Slender, threadlike family of ALGAE, in the order Charales, that are closely related to PLANTS. They differ from GREEN ALGAE in that they grow upright with branches off a central stand.
Canadian Medical Guide Definition Cryptophyta - A division (some say phylum or class) of the ALGAE, characterized by biflagellated cells and found in both freshwater and marine environments. Pigmentation varies but only one CHLOROPLAST is present. Unique structures include a nucleomorph and ejectosomes.
Canadian Medical Guide Definition Cyanophora - A genus of primitive ALGAE in the family Cyanophoraceae, class Glaucocystophyceae. They contain pigmented prokaryotic endosymbionts called cyanelles, which have characteristics of both CYANOBACTERIA and CHLOROPLASTS.
Canadian Medical Guide Definition Diatoms - The common name for the phylum of microscopic unicellular ALGAE. Most are aquatic, being found in fresh, brackish, and salt water. Diatoms are noted for the symmetry and sculpturing of their siliceous cell walls. They account for 40% of PHYTOPLANKTON, but not all diatoms are planktonic.
Canadian Medical Guide Definition Lichens - Any of a group of plants formed by a mutual combination of an alga and a fungus.
Canadian Medical Guide Definition Oomycetes - A group of ALGAE, formerly considered FUNGI, whose exact taxonmomic level is unsettled. Many consider Oomycetes (Oomycota) a phylum in the kingdom Stramenopila, or alternatively, as Pseudofungi in the phylum Heterokonta of the kingdom Chromista. They are morphologically similar to fungi but have no close phylogenetic relationship to them. Oomycetes are found in both fresh and salt water as well as in terrestrial environments. (Alexopoulos et al., Introductory Mycology, 4th ed, pp683-4). They produce flagellated, actively motile spores (zoospores) that are pathogenic to many crop plants and FISHES.
Canadian Medical Guide Definition Seaweed - Marine ALGAE widely distributed in the ocean, occurring from the tide level to considerable depths, free-floating (planktonic) or anchored to the substratum (benthic). They lack a specialized vascular system but take up fluids, nutrients, and gases directly from the water. They contain CHLOROPHYLL and are photosynthetic, but some also contain other light-absorbing pigments. Many are of economic importance as FOOD, fertilizer, AGAR, potash, or source of IODINE.

Algae Medical Definitions and Terms

CANADIAN MEDICAL GUIDE

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