particle
1. A very small piece or portion of anything. 2. An elementary p. such as a proton or electron. [L. particula, dim. of pars, part]
- alpha p. (α) a p. consisting of two neutrons and two protons, with a positive charge (2e+); emitted energetically from the nuclei of unstable isotopes of high atomic number (elements of mass number from 82 up); identical to the helium nucleus. SYN: alpha ray.
- beta p. an electron, either positively (positron, β+) or negatively (negatron, β) charged, emitted during beta decay of a radionuclide. SEE ALSO: cathode rays, under ray. SYN: beta ray.
- chromatin particles fine bluish dots thought to represent remnants of the nucleus, occasionally seen in stained erythrocytes.
- core p. p. released by partial enzymatic digestion of chromatin.
- Dane particles the larger spherical forms of hepatitis-associated antigens; they compose the virion of hepatitis B virus, containing a 27-nm “core” in which DNA-dependent DNA polymerase and circular, double-stranded DNA have been found.
- defective interfering p. an incomplete virus that is unable to replicate and interferes with replication of an infectious virus.
- D.I. p. abbreviation for defective interfering p..
- electron transport particles (ETP) fragments of mitochondria still capable of transporting electrons. SYN: submitochondrial particles.
- elementary p. 1. SYN: platelet. 2. one of the units occurring on the matrical surface of mitochondrial cristae; the head of the p., which measures about 9 nm, attaches to the membrane of the crista by a stalk 5 nm long; the p. may be concerned with the electron transport system.
- kappa particles inheritable cytoplasmic symbionts, once thought to be particles mainly or exclusively of DNA, occurring in some strains of Paramecium; capable of producing a product lethal to other strains.
- signal recognition p. (SRP) a small RNA-protein complex that interacts with the signal sequence of nascent secretory proteins. Binding of the signal recognition p. results in arrest of translation until interaction with docking protein, an integral part of the endoplasmic reticulum membrane.
- submitochondrial particles SYN: electron transport particles.
- Zimmermann elementary p. obsolete term for platelet.

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par·ti·cle 'pärt-i-kəl n
1) one of the minute subdivisions of matter (as an atom or molecule) also ELEMENTARY PARTICLE
2) a minute quantity or fragment

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par·ti·cle (pahrґtĭ-kəl) [L. particula, dim. of pars part] a tiny mass of material.

Medical dictionary. 2011.

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  • particle — 1 Particle, bit, mite, smidgen, whit, atom, iota, jot, tittle all mean a very small or insignificant piece or part. Particle is used in reference not only to substances which are actually divisible but to such things as a quality, a state, or a… …   New Dictionary of Synonyms

  • Particle — may refer to:In chemistry: * Colloidal particle, part of a one phase system of two or more componentsIn physics: * Subatomic particle, which may be either: **Elementary particle, a particle of which larger particles are composed, also called a… …   Wikipedia

  • Particle — Par ti*cle, n. [L. particula, dim. of pars, gen partis, a part: cf. F. particule. See {Part}, and cf. {Parcel}.] 1. A minute part or portion of matter; a morsel; a little bit; an atom; a jot; as, a particle of sand, of wood, of dust. [1913… …   The Collaborative International Dictionary of English

  • particle — [pärt′i kəl] n. [ME partycle < MFr particule < L particula, dim. of pars,PART1] 1. a) an extremely small piece; tiny fragment [a dust particle] b) the slightest trace; speck [not a particle of truth] 2 …   English World dictionary

  • particle — (n.) late 14c., small part or division of a whole, from L. particula little bit or part, dim. of pars (gen. partis); see PART (Cf. part) (n.). In construction, particle board (1957) is so called because it is made from chips and shavings of wood …   Etymology dictionary

  • particle — index constituent (part), element, iota, minimum, modicum, part (portion), scintilla …   Law dictionary

  • particle — [n] atom, piece bit, crumb, dot, dribble, drop, fleck, fragment, grain, hoot*, iota, jot, minim, mite, modicum, molecule, morsel, mote, ounce, ray, scrap, scruple, seed, shred, smidgen, smithereen, speck, spot, stitch, whit; concept 831 …   New thesaurus

  • particle — ► NOUN 1) a minute portion of matter. 2) Physics a component of the physical world smaller than an atom, e.g. an electron, proton, neutrino, or photon. 3) Grammar a minor function word that has comparatively little meaning and does not inflect, e …   English terms dictionary

  • particle — particled, adj. /pahr ti keuhl/, n. 1. a minute portion, piece, fragment, or amount; a tiny or very small bit: a particle of dust; not a particle of supporting evidence. 2. Physics. a. one of the extremely small constituents of matter, as an atom …   Universalium

  • particle — [[t]pɑ͟ː(r)tɪk(ə)l[/t]] particles 1) N COUNT: oft N of n A particle of something is a very small piece or amount of it. ...a particle of hot metal... There is a particle of truth in his statement. ...food particles. 2) N COUNT In physics, a… …   English dictionary

  • particle */*/ — UK [ˈpɑː(r)tɪk(ə)l] / US [ˈpɑrtɪk(ə)l] noun [countable] Word forms particle : singular particle plural particles 1) an extremely small piece or amount of something dust particles particle of: tiny particles of food There s not a particle of… …   English dictionary

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