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mitosis

(Encyclopedia)CE5 Mitosis in a body cell of an animal mitosis mītōˈsĭs, mĭ– [key], process of nuclear division in a living cell by which the carriers of hereditary information, or the chromosomes, are ex...

catabolism

(Encyclopedia)catabolism kətăbˈəlĭzˌəm [key], subdivision of metabolism involving all degradative chemical reactions in the living cell. Large polymeric molecules such as polysaccharides, nucleic acids, and ...

Schwann, Theodor

(Encyclopedia)Schwann, Theodor tāˈōdōr shvän [key], 1810–82, German physiologist and histologist. He was a student of J. P. Müller and professor at the universities of Louvain (1838–48) and Liège (from 1...

Yerkes, Robert Mearns

(Encyclopedia)Yerkes, Robert Mearns yûrˈkēz [key], 1876–1956, American psychologist, b. Bucks co., Pa., grad. Harvard (B.A. 1898; Ph.D.1902). He taught (1902–17) at Harvard, served (1919–24) on the Nationa...

mitochondria

(Encyclopedia)mitochondria: see cell.

nucleolus

(Encyclopedia)nucleolus: see cell.

behavior

(Encyclopedia)behavior, in biology: see ethology. ...

stem cells

(Encyclopedia)stem cells, unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastu...

paramecium

(Encyclopedia)paramecium parəmēˈsĭəm [key], unicellular organism of the genus Paramecium, of the ciliate phylum Ciliophora found in freshwater throughout the world. Like other protozoans, paramecia, previously...

melanin

(Encyclopedia)melanin mĕlˈənĭn [key], water-insoluble polymer of various compounds derived from the amino acid tyrosine. It is one of two pigments found in human skin and hair and adds brown to skin color; the ...