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lung cancer

(Encyclopedia)lung cancer, cancer that originates in the tissues of the lungs. Lung cancer is the leading cause of cancer death in the United States in both men and women. Like other cancers, lung cancer occurs aft...

crossing over

(Encyclopedia)crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each ...

Kircher, Athanasius

(Encyclopedia)Kircher, Athanasius ätänäˈzēo͝os kĭrkhˈər [key], 1601?–1680, German Jesuit archaeologist, mathematician, biologist, philologist, astronomer, musicologist, and physicist. One of the world's ...

collagen

(Encyclopedia)collagen kŏlˈəjən [key], any of a group of proteins found in skin, ligaments, tendons, bone and cartilage, and other connective tissue. Cells called fibroblasts form the various fibers in connecti...

Brenner, Sydney

(Encyclopedia)Brenner, Sydney, 1927–2019, British molecular biologist, Ph.D. Oxford, 1954. He was director of the MRC Laboratory of Molecular Biology in Cambridge, England (1979–86), and director of the MRC Mol...

biology

(Encyclopedia)biology, the science that deals with living things. It is broadly divided into zoology, the study of animal life, and botany, the study of plant life. Subdivisions of each of these sciences include cy...

Tombaugh, Clyde William

(Encyclopedia)Tombaugh, Clyde William tŏmˈbô [key], 1906–97, American astronomer, b. Streator, Ill. Although lacking formal training or a college degree, he was hired in 1929 as an assistant by the Lowell Obse...

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...

zoology

(Encyclopedia)zoology, branch of biology concerned with the study of animal life. From earliest times animals have been vitally important to man; cave art demonstrates the practical and mystical significance animal...

quartz

(Encyclopedia)quartz, one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2. It occurs in crystals of the hexagon...