another Alu famil a dispersed intermediately repetitive DNA sequence found in the human genome in about three hundred thousand copies. The sequence is about 300 bp long. The name Alu comes from the restriction endonuclease alul that cleaves it amber codon The codon UAG, a nonsense codon amber suppressor a mutant allele coding for a tRNa whose anticodon is altered in such a way that the suppressor tRNA inserts an amino acid at an amber codon in translation suppressing (preventing)termination Ames test A widely used test to detect possible chemical carcinogens based on mutagenicity in the bacterium Salmonella amino acid The basic building block of proteins (or polypeptides). Containing a basic amino(NH2) group, an acidic carboxyl( COOH) group and a side chain(R-of a number of different kinds)attached to an alpha carbon atom. Thus NH2-C-CO0H aminoacyl-tRNA Transfer RNA (tRNA) molecule with its cognate amino acid attached aminoacyl-tRNA synthetase enzyme that attaches an amino acid to its cognate tRNA(S) amniocentesis a technique for testing the genotype of an embryo or fetus in utero with minimal risk to the mother or the child amorph A mutant showing the complete lack of some normal substance or structure AMP Adenosine monophosphateanother. Alu family A dispersed intermediately repetitive DNA sequence found in the human genome in about three hundred thousand copies. The sequence is about 300 bp long. The name Alu comes from the restriction endonuclease AluIthat cleaves it. amber codon The codon UAG, a nonsense codon. amber suppressor A mutant allele coding for a tRNA whose anticodon is altered in such a way that the suppressor tRNA inserts an amino acid at an amber codon in translation suppressing (preventing) termination. Ames test A widely used test to detect possible chemical carcinogens; based on mutagenicity in the bacterium Salmonella. amino acid The basic building block of proteins (or polypeptides). Containing a basic amino (NH2) group, an acidic carboxyl (COOH) group and a side chain (R - of a number of different kinds) attached to an alpha carbon atom. Thus: R | NH2-C-COOH | H aminoacyl-tRNA Transfer RNA (tRNA) molecule with its cognate amino acid attached. aminoacyl-tRNA synthetase enzyme that attaches an amino acid to its cognate tRNA(s). amniocentesis A technique for testing the genotype of an embryo or fetus in utero with minimal risk to the mother or the child. amorph A mutant showing the complete lack of some normal substance or structure. AMP Adenosine monophosphate