| CA | anterior commissure [Lat. commissura anterior]; calcium antagonist; California [rabbit]; cancer; Can... |
|---|---|
| CEC | central echo complex; ciliated epithelial cell; Commission of the European Community |
| CL | capillary lumen; cardiolipin; cell line; centralis lateralis; chemiluminescence; chest and left arm ... |
| ECHO | echocardiography; enteric cytopathic human orphan [virus]; Etoposide, cyclophosphamide, Adriamycin, ... |
| Echo-Eg | echoencephalography |
| signal sequence | A peptide present on proteins that are destined either to be secreted or to be membrane components. It is usually at the N terminus and normally absent from the mature protein. Normally refers to the sequence (ca 20 amino acids) that interacts with signal recognition particle and directs the ribosome to the endoplasmic reticulum where co translational insertion takes place. Could also refer to sequences that direct post translational uptake by organelles. Signal peptides are highly hydrophobic but with some positively charged residues. The signal sequence is normally removed from the growing peptide chain by signal peptidase, a specific protease located on the cisternal face of the endoplasmic reticulum. See: signal recognition particle. (18 Nov 1997) |
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| signature sequence | Short oligonucleotides of unique sequence found in 16S ribosomal RNA of a particular group of prokaryotes. (09 Oct 1997) |
| disruption sequence | The events that occur when a foetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus. (12 Dec 1998) |
| DNA sequence | <molecular biology> The relative order of base pairs, whether in a fragment of DNA, a gene, a chromosome, or an entire genome. See: base sequence analysis. (09 Oct 1997) |
| DNA sequence analysis | <molecular biology> Determination of the nucleotide sequence of a length of DNA. Typically, this is performed by cloning the DNA of interest, so that enough can be prepared to allow the sequence to be determined, usually by the Sanger dideoxy chain temination or Maxam Gilbert chain degradation techniques. The resulting reactions are then run on a large sequencing gel, capable of resolving single nucleotide differences in chain length. Recently, PCR based methods have obviated the need to clone the DNA under some conditions and automated DNA sequencing has become widely available. (18 Nov 1997) |
| DNA sequence, unstable | DNA region comprised of a variable number of repetitive, contiguous trinucleotide sequences. Presence of these regions is associated with diseases such as fragile x syndrome and myotonia atrophica. (12 Dec 1998) |
| insertion sequence | Mobile nucleotide sequences that occur naturally in the genomes of bacterial populations. When inserted into bacterial DNA, they inactivate the gene concerned, when they are removed the gene regains its activity. Closely related to transposons and range in size from a few hundred to a few thousand bases, but are usually less than 1500 bases. (18 Nov 1997) |
| intervening sequence | <molecular biology> Alternative but uncommon name for an intron. (18 Nov 1997) |
| tandem repeat sequence | <molecular biology> Multiple copies of the same base sequence on a chromosome, used as a marker in physical mapping. (09 Oct 1997) |
| termination sequence | <molecular biology> The three codons, UAA known as ochre, UAG as amber and UGA as opal, that do not code for an amino acid but act as signals for the termination of protein synthesis. They are not represented by any tRNA and termination is catalysed by protein release factors. There are two release factors in E. Coli, RF1 recognises UAA and UAG, RF2 recognises UAA and UGA. Eukaryotes have a single GTP requiring factor, eRF. See: ochre suppressor, amber suppressor. (13 Jan 1998) |
| enhancer sequence | <molecular biology> A nucleotide sequence, located as many as several thousand base pairs away in either direction from the target gene, which enhances transcription of that gene. (14 Nov 1997) |
| evolutionarily conserved sequence | A base sequence in a DNA molecule (or an amino acid sequence in a protein) that has remained essentially unchanged throughout evolution. (12 Dec 1998) |
| Expressed Sequence Tag | <molecular biology> Expressed sequence tags are sequence tagged sites derived from cDNAs. See: sequence tagged site. Acronym: EST (06 Aug 1998) |
| flanking sequence | <molecular biology> Short DNA sequences bordering a transcription unit. Often these do not code for proteins. (18 Nov 1997) |
| leader sequence | <molecular biology> In the regulation of gene expression for enzymes concerned with amino acid synthesis in prokaryotes, the leader sequence codes for the leader peptide that contains several residues of the amino acid being regulated. Transcription is closely linked to translation and if translation is retarded by limited supply of amino acyl tRNA for the specific amino acid, the mode of transcription of the leader sequence permits full transcription of the operon genes, otherwise complete transcription of the leader sequence prematurely terminates transcription of the operon. (18 Nov 1997) |