| sequence hypothesis | Francis Crick's seminal concept that genetic information exists as alinear DNA code, DNA and protein sequence are colinear. (09 Oct 1997) |
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| sequence ladder | The array of bands, made conspicuous by labeling, when DNA fragmented by endonucleases is subject to gel electrophoresis; corresponds to the nucleotide sequence. (05 Mar 2000) |
| sequence pulse | In magnetic resonance imaging, the series of radiofrequency signals used to shift the magnetic field to change proton orientation. (05 Mar 2000) |
| sequence, regulatory | A sequence of bases in DNA that controls the expression of a gene. (12 Dec 1998) |
| sequence tagged site | <molecular biology> Short (200 to 500 base pairs) DNA sequence that has a single occurrence in the human genome and whose location and base sequence are known. Detectable by PCR, sequence tagged sites are useful for localising and orienting the mapping and sequence data reported from many different laboratories and serve as landmarks on the developing physical map of the human genome. Expressed sequence tags are sequence tagged sites derived from cDNAs. (11 Jun 1998) |
| sequence-tagged site map | A map representing the order and spacing of sequence-tagged sites within a stretch of DNA. (05 Mar 2000) |
| sequence tagged sites | Short, tagged tracts of DNA sequence that are used as landmarks in genome mapping. In most instances, 200 to 500 base pairs of sequence define a sequence tagged site (sts) that is operationally unique in the human genome (i.e., can be specifically detected by the polymerase chain reaction in the presence of all other genomic sequences). The overwhelming advantage of stss over mapping landmarks defined in other ways is that the means of testing for the presence of a particular sts can be completely described as information in a database. (12 Dec 1998) |
| sequence-tagged sites | Short stretches of DNA sequences that can be detected by use of the polymerase chain reaction. (05 Mar 2000) |
| pyrimidine-guanine sequence-specific ribonuclease | <enzyme> From yolk granules of adult rana catesbeiana oocytes Registry number: EC 3.1.27.- Synonym: rc-rnase, rana catesbeiana rnase (26 Jun 1999) |
| shine-dalgarno sequence | A short stretch of nucleotides on a prokaryotic mRNA molecule upstream of the translational start site, that serves to bind to ribosomal RNA and thereby bring the ribosome to the initiation codon on the mRNA. (09 Oct 1997) |
| 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) |
| 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) |