Columbia Encyclopedia

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drugs

(Encyclopedia)drugs, substances used in medicine either externally or internally for curing, alleviating, or preventing a disease or deficiency. At the turn of the century only a few medically effective substances ...

protein

(Encyclopedia)protein, any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellu...

nucleic acid

(Encyclopedia)CE5 Replication of strands of DNA CE5 nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replica...

water pollution

(Encyclopedia)water pollution, contamination of water resources by harmful wastes; see also sewerage, water supply, pollution, and environmentalism. The United States has enacted extensive federal legislation to ...

genetics

(Encyclopedia)genetics, scientific study of the mechanism of heredity. While Gregor Mendel first presented his findings on the statistical laws governing the transmission of certain traits from generation to genera...

cancer, in medicine

(Encyclopedia)cancer, in medicine, common term for neoplasms, or tumors, that are malignant. Like benign tumors, malignant tumors do not respond to body mechanisms that limit cell growth. Unlike benign tumors, mali...

ocean

(Encyclopedia)ocean, interconnected mass of saltwater covering 70.78% of the surface of the earth, often called the world ocean. It is subdivided into four (or five) major units that are separated from each other i...