BacteriaOne of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophic (via chemical reaction) or phototrophic (via light reaction); for chemotrophs by their source of chemical energy: lithotrophic (from inorganic compounds) or organotrophic (from organic compounds); and by where they get their CARBON: heterotrophic (from organic sources) or autotrophic (from CARBON DIOXIDE). They can also be classifed by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.
LifeThe state that distinguishes organisms from inorganic matter, manifested by growth, metabolism, reproduction, and adaptation. It includes the course of existence, the sum of experiences, the mode of existing, or the fact of being. Over the centuries inquiries into the nature of life have crossed the boundaries from philosophy to biology, forensic medicine, anthropology, etc., in creative as well as scientific literature. (Random House Unabridged Dictionary, 2d ed; Dr. James H. Cassedy, NLM History of Medicine Division)
BacteriaOne of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophic (via chemical reaction) or phototrophic (via light reaction); for chemotrophs by their source of chemical energy: lithotrophic (from inorganic compounds) or organotrophic (from organic compounds); and by where they get their CARBON: heterotrophic (from organic sources) or autotrophic (from CARBON DIOXIDE). They can also be classifed by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.
LightThat portion of the electromagnetic spectrum to which the human eye is sensitive. Light is about 400 to 800 nanometers in wavelength, i.e., between the ultraviolet and infrared spectra.
CarbonA nonmetallic element with atomic symbol C, atomic number 6, and atomic weight 12.011. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE.
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