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Gram's stain

(Encyclopedia)Gram's stain, laboratory staining technique that distinguishes between two groups of bacteria by the identification of differences in the structure of their cell walls. The Gram stain, named after its...

carbon cycle

(Encyclopedia)CE5 Carbon cycle carbon cycle, in biology, the exchange of carbon between living organisms and the nonliving environment. Inorganic carbon dioxide in the atmosphere is converted by plants into sim...

spore

(Encyclopedia)spore, 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...

diatom

(Encyclopedia)diatom dīˈətŏmˌ, –tōmˌ [key], unicellular organism of the kingdom Protista, characterized by a silica shell of often intricate and beautiful sculpturing. Most diatoms exist singly, although s...

membrane

(Encyclopedia)membrane, structure composed mostly of lipid and protein that forms the external boundary of cells and of major structures within cells. Membrane organization is based on a sheet two molecules thick�...

Haldane, John Burdon Sanderson

(Encyclopedia)Haldane, John Burdon Sanderson hôlˈdān, –dən [key], 1892–1964, British geneticist, biologist, and popularizer of science; son of John Scott Haldane. He studied at Oxford until his studies were...

animal

(Encyclopedia)animal, any member of the animal kingdom (kingdom Animalia), as distinguished from organisms of the plant kingdom (kingdom Plantae) and the kingdoms Fungi, Protista, and Monera in the five-kingdom sys...

episome

(Encyclopedia)episome ĕpˈĭsōm [key], unit of genetic material composed of a series of genes that sometimes has an independent existence in a host cell and at other times is integrated into a chromosome of the c...

liposome

(Encyclopedia)liposome līˈpəsōmˌ, lĭpˈə– [key], microscopic, fluid-filled pouch whose walls are made of layers of phospholipids identical to the phospholipids that make up cell membranes. Liposomes are us...

Hartwell, Leland Harrison

(Encyclopedia)Hartwell, Leland Harrison, 1939–, American cell biologist, b. Los Angeles, Ph.D. Massachusetts Institute of Technology, 1964. He is a professor at the Univ. of Washington (1968–) and since 1997 ha...