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Definition: spore from The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide

Small reproductive or resting body, usually consisting of just one cell. Unlike a gamete, it does not need to fuse with another cell in order to develop into a new organism. Spores are produced by the lower plants, most fungi, some bacteria, and certain protozoa. They are generally light and easily dispersed by wind movements.

Plant spores are haploid (having a single set of chromosomes in each cell) and are produced by the sporophyte, following meiosis; see alternation of generations.

Bacterial (for example, anthrax) spores pose a threat because they may be resistant to common sterilization procedures, and because they could be treated to create powerful biological weapons.

Summary Article: spore
From The Columbia Encyclopedia

term applied both to a resistant or resting stage occurring among various unicellular organisms (especially bacteria) and to an asexual reproductive cell produced by many unicellular plants and animals and by all plants that undergo an alternation of generations. A spore is typically a cell surrounded by a cell wall; in resistant spores and in the resting stage of reproductive spores this wall becomes tough and waterproof, permitting the cell to survive unfavorable circumstances such as extremes of temperature and moisture. Upon germination, spores that were generated asexually may produce cells or multicellular forms that can engage in sexual reproduction. Many unicellular plants and animals reproduce both by the formation of spores and by simple cell division (mitosis). Yeasts, for instance, reproduce by forming spores as well as by budding. Among the fungi some spores are thin-walled and germinate quickly; others are thick-walled resistant types. In multicellular plants the sporophyte generation produces (by meiosis) spores with half the normal number of chromosomes for the species; these grow directly into the gametophyte generation, which produces (by mitosis) male and female reproductive cells that when united give rise to a sporophyte.

The Columbia Encyclopedia, © Columbia University Press 2018

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