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nuclein

(nū′klē-ĭn) [L. nucleus, a kernel] The breakdown product of the nucleoproteins of chromosomes.

nuclein base

Any of the bases formed from decomposition of nuclein, such as adenine, guanine, xanthine, and hypoxanthine.

nucleo-, nucle-, nuclei-

[L. nucleus, kernel] Prefix meaning nucleus.

nucleocapsid

(nū″klē-ō-kăp′sĭd) In a virus, the protein coat and the viral nucleic acid.

nucleofugal

(nū-klē-ŏf′ū-găl) [″ + fugere, to flee] Directed or moving away from a nucleus.

nucleohistone

(nū″klē-ō-hĭs′tŏn, -tōn) [″ + Gr. histos, tissue] A substance composed of nuclein and histone, found in sperm of various animals.

nucleoid

(nū′klē-oyd) [″ + Gr. eidos, form, shape] Resembling a nucleus.

nucleoloid

(nū′klē-ō-loyd) Similar to a nucleus.

nucleolonema

(nū″klē-ō″lō-nē′mă) [″ + Gr. nema, thread] A fine network in the nucleolus of a cell.

nucleolus

(nū-klē′ō-lŭs) pl. nucleoli [L., little kernel] A spherical structure in the nucleus of a cell made of DNA, RNA, and protein. It is the site of synthesis of ribosomal RNA (rRNA); a cell may have more than one. Embryonic cells and those in malignancies actively synthesize rRNA; therefore, their nucleoli are larger than those of cells that do not require increased amounts of rRNA. nucleolar (nū-klē′ō-lăr), adj.

nucleon

(nū′klē-ŏn) Any of the particles that collectively make up the nucleus of an atom.

nucleopetal

(nū-klē-ŏp′ĕ-tăl) [L. nucleus, kernel, + petere, to seek] Seeking or moving toward the nucleus.

nucleophilic

(nū″klē-ō-fĭl′ĭk) [″ + Gr. philein, to love] Having an attraction to nuclei.

nucleoplasm

(nū′klē-ō-plăzm″) [″ + L. plasma, form, mold] The protoplasm of a cell nucleus. nucleoplasmic, adj.

nucleoprotein

(nū″klē-ō-prō′tē-ĭn) [″ + Gr. protos, first] The combination of protein and nucleic acid (DNA or RNA).

nucleosidase

(nū″klē-ō-sī′dās) An enzyme that catalyzes the hydrolysis of nucleosides.

nucleoside

(nū′klē-ō-sīd) A glycoside formed by the union of a purine or pyrimidine base with a sugar (pentose).

nucleosome

(nū′klē-ō-sōm) The combination of positively charged histone proteins and negatively charged DNA; the first step in the folding of DNA into chromatin.

nucleospindle

(nū″klē-ō-spĭn′d’l) A spindle-shaped body occurring in karyokinesis.

nucleotidase

(nū″klē-ŏt′ĭ-dās) An enzyme (nucleophosphatase) that splits phosphoric acid from nucleotides, leaving a nucleoside.

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