Columbia Encyclopedia

Search results

500 results found

coenzyme

(Encyclopedia)coenzyme kō-ĕnˈzīm [key], any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a ...

oxide

(Encyclopedia)oxide, chemical compound containing oxygen and one other chemical element. Oxides are widely and abundantly distributed in nature. Water is the oxide of hydrogen. Silicon dioxide is the major componen...

Human Genome Project

(Encyclopedia)Human Genome Project, international scientific effort to map all of the genes on the 23 pairs of human chromosomes and, to sequence the 3.1 billion DNA base pairs that make up the chromosomes (see nuc...

exobiology

(Encyclopedia)exobiology or astrobiology, search for extraterrestrial life within the solar system and throughout the universe. Philosophical speculation that there might be other worlds similar to ours dates back ...

chyme

(Encyclopedia)chyme kīm [key], semiliquid substance found in the stomach and resulting from the partial digestion of food by the salivary enzyme amylase, the gastric enzyme pepsin, and hydrochloric acid. Secretion...

sodium nitrate

(Encyclopedia)sodium nitrate, chemical compound, NaNO3, a colorless, odorless crystalline compound that closely resembles potassium nitrate (saltpeter or niter) in appearance and chemical properties. It is soluble ...

pellagra

(Encyclopedia)pellagra pəlăgˈrə [key], deficiency disease due to a lack of niacin (nicotinic acid), one of the components of the B complex vitamins in the diet. Niacin is plentiful in yeast, organ meats, peanut...

carambola

(Encyclopedia)carambola kărˌəmbōˈlə [key], orange fleshy fruit of Averrhoa carambola, a small shrub in the wood sorrel family (Oxalidaceae). The fruits have five very prominent ridges, and in transverse secti...

lemon

(Encyclopedia)lemon, one of the citrus fruits, from a tree (Citrus limon) of the family Rutaceae (orange family), probably native to India. A small tree (to about 15 ft/5 m tall) with thorny branches and purple-edg...

carbonate

(Encyclopedia)carbonate kärˈbənātˌ, –nət [key], chemical compound containing the carbonate radical or ion, CO3−2. Most familiar carbonates are salts that are formed by reacting an inorganic base (e.g., a ...