cytochrome Vsi-to-.kroirA Any of a group of cell proteins (hemopro- teins) that serve a vital function in the transfer of energy within cells. Hemoproteins are linked to a nonprotein, iron-bearing component (a heme group), which can undergo the reversible oxidation-reduction reactions that yield energy for the cell. Cytochromes are subdivided into three classes depending on what wavelengths of light they absorb. At least 30 differ¬ ent cytochromes have been identified.
cytology \si-'ta-l3-je\ Study of cells. Its earliest phase began with Rob¬ ert Hooke’s microscopic investigations of cork in 1665, during which he introduced the term cell to describe dead cork cells. Mathias Jacob
Schleiden (in 1838) and Theodor Schwann (1839) were among the first to state clearly that cells are the fundamental units of both plants and ani¬ mals. This pronouncement (the cell theory) was confirmed and elaborated by a series of discoveries and interpretations. In 1892 Oscar Hertwig (1849-1922) suggested that processes at the organism’s level are reflec¬ tions of cellular processes, thus establishing cytology as a separate branch of biology. See also physiology.
cytomegalovirus (CMV) Any of several viruses in the herpes family. Active infection produces enlarged cells enclosing foreign matter. Most prevalent in crowded, poor communities, it is transmitted by sexual con¬ tact or infected body fluids. It rarely causes serious illness in healthy adults; however, it can lead to serious consequences, including blindness, in those with depressed immune systems. In newborns, even without spleen and liver enlargement (10% of cases), CMV is the most common infection and a major cause of congenital deafness; it may also induce retardation and blindness. There is no effective treatment.
cytoplasm VsI-to-.pla-zomV Portion of a eukaryotic cell outside the nucleus. The cytoplasm contains all the organelles (see eukaryote). The organelles include the mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes. The cytoplasm also contains the cytoskeleton and the cytosol (the fluid mass that surrounds the vari¬ ous organelles).
cytosine Vsl-t3-,sen\ Organic compound of the pyrimidine family, often called a base, consisting of a single ring, containing both nitrogen and carbon atoms, and an amino group. It occurs in combined form in nucleic acids and several coenzymes. In DNA its complementary base is guanine. It or its corresponding nucleoside or nucleotide may be prepared from DNA by selective techniques of hydrolysis.
cytoskeleton \'sl-t3-,ske-l3-t®n\ System of microscopic filaments or fibres, present in the cytoplasm of eukaryotic cells (see eukaryote), that organizes other cell components, maintains cell shape, and is responsible for cell locomotion and for movement of the organelles within it. Three major types of filaments make up the cytoskeleton: actin filaments, micro¬ tubules, and intermediate filaments. Actin filaments occur as constantly changing bundles of parallel fibres; they help determine cell shape, help the cell adhere to surfaces, help the cell move, and assist in cell division during mitosis. Intermediate filaments are very stable structures that form the cell’s true skeleton; they anchor the nucleus within the cell and give the cell its elastic properties.
czar See tsar
Czartoryski family \char-to-'ris-ke\ Leading noble family of Poland in the 18th century, known as the Familia. It first achieved widespread power through the efforts of Prince Michal Fryderyk Czartoryski (1696— 1775) and his brother August. The Familia, which sought the enactment of constitutional reforms, attained the height of its influence in the court of Augustus III. The family estate at Pulawy was confiscated in 1794, dur¬ ing the third Partition of Poland. However, the Familia continued to wield significant power, notably through the princes Adam Kazimierz Czarto¬ ryski (1734-1823), a patron of the arts, and Adam Jerzy Czartoryski (1770-1861), who worked for the restoration of Poland.
Czech language formerly Bohemian language West Slavic lan¬ guage spoken by some 12 million people in the historical regions of Bohemia, Moravia, and southwestern Silesia, all now in the Czech Repub¬ lic, and in emigre communities, including perhaps a million speakers in North America. The earliest Old Czech texts date from the late 13th cen¬ tury. The distinctive orthographic system of Czech, which adds diacritics to letters of the Latin alphabet to denote consonants that did not exist in Latin and to mark vowel length, was introduced in the early 15th century and is associated with the religious reformer Jan Hus. The system was later adopted by other Slavic languages that use the Latin alphabet, includ¬ ing Slovak, Slovene, and Croatian (see Serbo-Croatian language). When Czech was revived as a literary language in the early 19th century, Josef DoBROVSKy based his codification of the language largely on the norms of 16th-century Czech, as exemplified in the Kralice Bible (1579-93), an authoritative translation. This decision has resulted in a wide gulf between Standard Czech, the literary language, and Common Czech, the spoken language.
Czech Republic formerly (1918-92, with Slovakia) Czechoslova¬ kia Country, central Europe. Area: 30,450 sq mi (78,866 sq km). Popu¬ lation (2005 est.): 10,221,000. Capitaclass="underline" Prague. Czechs make up nine-
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Czerny ► Czestochowa i 503
tenths of the population; Slovaks and Moravians are the largest minorities. Lan¬ guage: Czech (official). Religion: Chris¬ tianity (predominantly Roman Catholic, also other Christians, Protestant). Cur¬ rency: koruna. The landlocked country is dominated by the Bohemian Massif, a ring of mountains rising to 5,256 ft (1,602 m) at Mount Snezka to encircle the Bohemian Plateau. The Morava River valley, known as the
Moravian Corridor, separates the Bohemian Massif from the Carpathian Mountains. Woodlands are a characteristic feature of the Czech landscape; most regions have a moderate oceanic climate. The economy has been privatized since the collapse of communism and is now largely market- oriented. The Czech Republic is a multiparty republic with two legisla¬ tive houses; its chief of state is the president, and the head of government is the prime minister. Until 1918 its history was largely that of Bohemia. In that year the independent republic of Czechoslovakia was bom through the union of Bohemia and Moravia with Slovakia. Czechoslovakia came under the domination of the Soviet Union after World War II, and from 1948 to 1989 it was ruled by a communist government. Its growing politi¬ cal liberalization was suppressed by a Soviet invasion in 1968 (see Pra¬ gue Spring). After communist rule collapsed in 1989-90, separatist sentiments emerged among the Slovaks, and in 1992 the Czechs and Slo¬ vaks agreed to break up their federated state. At midnight on Dec. 31, 1992, Czechoslovakia was peacefully dissolved and replaced by two new countries, the Czech Republic and Slovakia, with the region of Moravia remaining in the former. In 1999 the Czech Republic joined NATO, and in 2004 it became a member of the European Union.
Czerny \'cher-ne\, Karl (b. Feb. 20, 1791, Vienna, Austria—d. July 15, 1857, Vienna) Austrian composer, teacher, and pianist. Son of a musician, he made his piano debut at age 9 and began study with Ludwig van Beethoven at 10. A brilliant pianist, he later became a famous piano teacher; his students included Sigismond Thalberg (1812-71) and Franz Liszt. Though he was a prolific composer, he is known today almost exclu¬ sively for his hundreds of piano exercises and etudes.