| q | <genetics> The symbol representing the long arm of a chromosome. (09 Oct 1997) |
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| Q angle | <anatomy> The angle formed by lines representing the resultant pull of the quadriceps muscle and the axis of the patellar tendon. (05 Mar 2000) |
| q arm | <cell biology> The long arm of a chromosome. All human chromosomes have 2 arms: the short (p) arm and the long (q) arms. (12 Dec 1998) |
| Q bands | <cell biology> The alternating bright and dull fluorescent bands seen on chromosomes under ultraviolet light after the chromosomes are stained with quinacrine. The Q stands for quinacrine, an agent used as an antimalarial agent and, in the laboratory, as a fluorescent dye. (12 Dec 1998) |
| q beta phage | <molecular biology> A single-stranded RNA phage that specifically infects enterobacteria containing the f plasmid. It is widely used to study RNA phage and bacterial cell function. (10 Oct 1997) |
| q beta replicase | <enzyme> An enzyme that catalyses the replication of the RNA of coliphage q beta. Registry number: EC 2.7.7.- (12 Dec 1998) |
| Q disks | The dark-staining anisotropic cross striations in the myofibrils of muscle fibres, comprising regions of overlapping thick (myosin) and thin (actin) filaments. Synonym: A disks, anisotropic disks, Q bands, Q disks. (05 Mar 2000) |
| Q enzyme | <enzyme> Converts amylose to amylopectin. (10 Oct 1997) |
| Q fever | <infectious disease> An acute (abrupt-onset), self-limited febrile illness first reported in 1935 in Queensland, Australia. The Q is said not to be for Queensland, but for query since the cause of the disease was long a query (question mark). It is caused by the bacterium Coxiella burnetii, a rickettsia which mainly afflicts sheep and cattle but can be transmitted to humans who have contact with infected animals. Symptoms resemble those of influenza and include sudden onset of fever, headache, malaise, and pneumonia (interstitial pneumonitis) but no rash. (12 Dec 1998) |
| q in population genetics | The frequency of the less common of two different alternative (allelic) versions of a gene. (the frequency of the more common allele is p). (12 Dec 1998) |
| Q tip test | A test for determining the mobility of the urethra. (05 Mar 2000) |
| Q wave | The initial deflection of the QRS complex when such deflection is negative (downward). (05 Mar 2000) |
| Q-banding | <cell biology, technique> A fluorescent stain for chromosomes which produces specific banding patterns for each pair of homologous chromosomes. The acridine dye derivative, quinacrine hydrochloride, or other derivatives like quinacrine mustard dihydrochloride produces a green-yellow fluorescence at pH 4.5 in chromosome segments rich in constitutive heterochromatin with deoxyadenylate-deoxythymidilate (A-T) bases of DNA. The centromeric regions of human chromosomes 3, 4, and 13 are specifically stained, as are satellites of some acrocentric chromosomes and the end of the long arm of the Y chromosome. Banding patterns are similar to those obtained with G-banding stain and similar fluorescent stain results are seen with the antibiotics adriamycin and daunomycin, as well as the tertiary dyes butyl proflavine and dapi, and the bisbenzimidazole dye hoechst 33258. See: banding patterns, Q bands, quinacrine. Synonym: quinacrine chromosome banding stain. (12 Jul 2000) |
| q-factor | <radiobiology> Ratio of power produced by fusion to power put into the reactor to heat the plasma and drive the magnetic fields. Q = 1 is the definition of scientific breakeven, where power out = power in. Economical fusion will require Q significantly greater than 1. Fortunately Q increases dramatically as the plasma parameters approach the Lawson criterion for ignition. Power to drive the magnetic fields is frequently ignored in discussions of Q, with the justification that a steady-state, continuous-output fusion reactor will have superconducting magnet coils. (15 Dec 1997) |
| Q-H2 | Symbol for ubiquinol. (05 Mar 2000) |