Columbia Encyclopedia

Search results

404 results found

bacteriophage

(Encyclopedia)bacteriophage băktērˈēəfājˌ [key], virus that infects bacteria and sometimes destroys them by lysis, or dissolution of the cell. Bacteriophages, or phages, have a head composed of protein, an i...

blood transfusion

(Encyclopedia)blood transfusion, transfer of blood from one person to another, or from one animal to another of the same species. Transfusions are performed to replace a substantial loss of blood and as supportive ...

antibiotic

(Encyclopedia)antibiotic, any of a variety of substances, usually obtained from microorganisms, that inhibit the growth of or destroy certain other microorganisms. Although for centuries preparations derived from ...

muscular dystrophy

(Encyclopedia)muscular dystrophy dĭsˈtrōfē [key], any of several inherited diseases characterized by progressive wasting of the skeletal muscles. There are five main forms of the disease. They are classified ac...

rat

(Encyclopedia)rat, name applied to various stout-bodied rodents, usually having a pointed muzzle, long slender tail, and dexterous forepaws. It refers particularly to the two species of house rat, Rattus norvegicus...

coral reefs

(Encyclopedia)coral reefs, limestone formations produced by living organisms, found in shallow, tropical marine waters. In most reefs, the predominant organisms are stony corals, colonial cnidarians that secrete an...

chronic fatigue syndrome

(Encyclopedia)chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME), collection of persistent, debilitating symptoms, the most notable of which is severe, lasting fatigue. It is also known as systemic ex...

urinary system

(Encyclopedia)CE5 Urinary system urinary system, group of organs of the body concerned with excretion of urine, that is, water and the waste products of metabolism. In humans, the kidneys are two small organs s...

protozoan

(Encyclopedia)protozoan prōˌtəzōˈən [key], informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms ...

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...