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Definition
 
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Alu Elements definition: The Alu sequence family (named for the restriction endonuclease cleavage enzyme Alu I) is the most highly repeated interspersed repeat element in humans (over a million copies). It is derived from the 7SL RNA component of the SIGNAL RECOGNITION PARTICLE and contains an RNA polymerase III promoter. Transposition of this element into coding and regulatory regions of genes is responsible for many heritable diseases.
Amino Acid Sequence definition: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
protein sequence definition: order of amino acids as they occur in a polypeptide chain.
amino acid sequence definition: The arrangement of amino acids in a protein. Proteins can be made from 20 different kinds of amino acids, and the structure and function of each type of protein are determined by the kinds of amino acids used to make it and how they are arranged.
Amino Acid Sequence definition: The sequence of amino acids along a polypeptide chain.
AT Rich Sequence definition: A nucleic acid sequence that contains an above average number of ADENINE and THYMINE bases.
Base Sequence definition: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
nucleic acid sequence definition: order of purines and pyrimidines in nucleic acids and polynucleotides.
Nucleotide Sequence definition: The sequence of nucleotide residues along an RNA or DNA chain.
Carbohydrate Sequence definition: The sequence of carbohydrates within POLYSACCHARIDES; GLYCOPROTEINS; and GLYCOLIPIDS.
carbohydrate sequence definition: sequence of carbohydrates within polysaccharides, glycoproteins, and glycolipids.
Conserved Sequence definition: A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.
genetic enhancer element definition: cis-acting DNA sequences which can increase transcription of genes; enhancers can usually function in either orientation and at various distances from a promoter.
Enhancer Elements, Genetic definition: Cis-acting DNA sequences which can increase transcription of genes. Enhancers can usually function in either orientation and at various distances from a promoter.
GC Rich Sequence definition: A nucleic acid sequence that contains an above average number of GUANINE and CYTOSINE bases.
Immunoglobulin Switch Region definition: A site located in the INTRONS at the 5' end of each constant region segment of a immunoglobulin heavy-chain gene where recombination (or rearrangement) occur during IMMUNOGLOBULIN CLASS SWITCHING. Ig switch regions are found on genes encoding all five classes (IMMUNOGLOBULIN ISOTYPES) of IMMUNOGLOBULIN HEAVY CHAINS.
Immunoglobulin Switch Region definition: A site on a segment of a B-cell immunoglobulin heavy-chain gene where recombination (or rearrangement) can occur. It is involved in isotype or allotype switching and maturation of the immune response. Ig switch regions are found on genes encoding all five immunoglobulin heavy chains.
Introns definition: Sequences of DNA in the genes that are located between the EXONS. They are transcribed along with the exons but are removed from the primary gene transcript by RNA SPLICING to leave mature RNA. Some introns code for separate genes.
intron definition: noncoding intervening sequence in a gene; separates the coding sequences.
Intron definition: Non-coding, intervening sequences of DNA that are transcribed, but are removed from within the primary gene transcript and rapidly degraded during maturation of messenger RNA.
Regulatory Sequences, Nucleic Acid definition: Nucleic acid sequences involved in regulating the expression of genes.
genetic regulatory element definition: binding sites on DNA for proteins that control genetic events; compare with STRUCTURAL GENE and REGULATORY GENE.
Regulatory Element definition: Any DNA sequence involved in the regulation of genetic processes such as transcription and replication.
Repetitive Sequences, Nucleic Acid definition: Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).
nucleic acid repetitive sequence definition: sequences of DNA or RNA that occur in multiple copies.
protein signal sequence definition: N-terminal, hydrophobic sequences which mediate the attachment of newly translated polypeptide chains to intracellular membranes; in some membrane proteins the signal peptide remains as a permanent anchor, while in secretory proteins it is cleaved.
Signal Peptide definition: The N-terminal sequence of a secreted protein that interacts with a signal recognition particle and is required for transport through the cell membrane.
Signal Peptides definition: Highly hydrophobic amino acid sequences of proteins that must cross through membranes to arrive at their functioning cellular location (such as secreted and membrane proteins). They are 15 to 60 amino acids long and reside at the amino-terminus (leader signal peptides) or internally. By binding to signal recognition particles, these sequences direct nascent protein-ribosome complexes to a membrane where the protein is inserted during translation. Signal peptides direct translational uptake of the protein by various membranes -endoplamic reticulum, mitochondrial, chloroplast, peroxisomal, etc. Leader signal sequences on non-membrane proteins are ultimately removed by specific peptidases.
Terminal Repeat Sequences definition: Nucleotide sequences repeated on both the 5' and 3' ends of a sequence under consideration. For example, the hallmarks of a transposon are that it is flanked by inverted repeats on each end and the inverted repeats are flanked by direct repeats. The Delta element of Ty retrotransposons and LTRs (long terminal repeats) are examples of this concept.
genetic terminator element definition: DNA sequences which signal the termination of transcription.
Terminator Regions, Genetic definition: DNA sequences recognized as signals to end GENETIC TRANSCRIPTION.
Consensus Sequence definition: A theoretical representative nucleotide or amino acid sequence in which each nucleotide or amino acid is the one which occurs most frequently at that site in the different sequences which occur in nature. The phrase also refers to an actual sequence which approximates the theoretical consensus. A known CONSERVED SEQUENCE set is represented by a consensus sequence. Commonly observed supersecondary protein structures (AMINO ACID MOTIFS) are often formed by conserved sequences.
Consensus Sequence definition: A sequence pattern derived from the alignment of multiple sequences that represents the nucleotide or amino acid most likely to occur at each position in a sequence. (Drug Discovery & Development, www.dddmag.com glossary)
Open Reading Frames definition: A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).
open reading frame definition: sequences of structural genes devoid of termination codons and therefore continuously "readable" by RNA polymerase.
Coding Region definition: The sequences on a gene or messenger RNA that are translated into protein.
Open Reading Frame definition: A sequence of nucleotides in that contains no termination codons and so can potentially translate as a polypeptide chain.
Repetitive Sequence definition: Nucleotide sequences present in multiple copies in the genome. There are several types of repeated sequences. Interspersed (or dispersed) DNA repeats (Interspersed Repetitive Sequences) are copies of transposable elements interspersed throughout the genome. Flanking (or terminal) repeats (Terminal Repeat Sequences) are sequences that are repeated on both ends of a sequence, for example, the long terminal repeats (LTRs) on retroviruses. Direct terminal repeats are in the same direction and inverted terminal repeats are opposite to each other in direction. Tandem repeats (Tandem Repeat Sequences) are repeated copies which lie adjacent to each other. These can also be direct or inverted. The ribosomal RNA and transfer RNA genes belong to the class of middle repetitive DNA.
DNA Sequence definition: The sequence of nucleotide residues along a DNA chain.
Minisatellite Repeats definition: Tandem arrays of moderately repetitive (5-50 repeats) short (10-60 bases) DNA sequences found dispersed throughout the genome and clustered near telomeres. Their degree of repetition is two to several hundred at each locus. Loci number in the thousands but each locus shows a distinctive repeat unit. Minisatellite repeats are often called variable number of tandem repeats.
Minisatellite Repeat definition: Tandem arrays of moderately repetitive (5-50 repeats) short (10-60 bases) DNA sequences found dispersed throughout the genome and clustered near telomeres. Their degree of repetition is two to several hundred at each locus. Loci number in the thousands but each locus shows a distinctive repeat unit.
DNA Sequence, Unstable definition: A region of DNA that is highly polymorphic and is prone to strand breaks, rearrangements or other MUTATIONS because of the nature of its sequence. These regions often harbor palindromic, or repetitive sequences (REPETITIVE SEQUENCES, NUCLEIC ACID). Variability in stability of the DNA sequence is seen at CHROMOSOME FRAGILE SITES.
Interspersed Repetitive Sequences definition: Copies of transposable elements interspersed throughout the genome, some of which are still active and often referred to as "jumping genes". There are two classes of interspersed repetitive elements. Class I elements (or RETROELEMENTS - such as retrotransposons, retroviruses, LONG INTERSPERSED NUCLEOTIDE ELEMENTS and SHORT INTERSPERSED NUCLEOTIDE ELEMENTS) transpose via reverse transcription of an RNA intermediate. Class II elements (or DNA TRANSPOSABLE ELEMENTS - such as transposons, Tn elements, insertion sequence elements and mobile gene cassettes of bacterial integrons) transpose directly from one site in the DNA to another.
5' Untranslated Regions definition: The sequence at the 5' end of the messenger RNA that does not code for product. This sequence contains the ribosome binding site and other transcription and translation regulating sequences.
5' Untranslated Region definition: Sequences on the 5' end of messenger RNAs that are not translated into protein. 5'UTR extends from the transcription start site to just before the ATG translation initiation codon. This region contains the ribosome binding site and other transcription and translation regulating sequences.
Long Interspersed Nucleotide Elements definition: Highly repeated sequences, 6K-8K base pairs in length, which contain RNA polymerase II promoters. They also have an open reading frame that is related to the reverse transcriptase of retroviruses but they do not contain LTRs (long terminal repeats). Copies of the LINE 1 (L1) family form about 15% of the human genome. The jockey elements of Drosophila are LINEs.
5' Flanking Region definition: The region of DNA which borders the 5' end of a transcription unit and where a variety of regulatory sequences are located.
3' Flanking Region definition: The region of DNA which borders the 3' end of a transcription unit and where a variety of regulatory sequences are located.
E-Box Elements definition: DNA locations with the consensus sequence CANNTG. ENHANCER ELEMENTS may contain multiple copies of this element. E-boxes play a regulatory role in the control of transcription. They bind with basic helix-loop-helix (bHLH) type TRANSCRIPTION FACTORS. Binding specificity is determined by the specific bHLH heterodimer or homodimer combination and by the specific nucleotides at the 3rd and 4th position of the E-box sequence.
AAUAAA RNA Sequence definition: A hexanucleotide sequence found 10-30 nucleotides upstream of the site of polyandenylation of MRNA.
Regulatory Sequences, Ribonucleic Acid definition: Sequences within RNA that regulate the processing, stability (RNA STABILITY) or translation (TRANSLATION, GENETIC) of RNA.
RNA 5' Terminal Oligopyrimidine Sequence definition: A regulatory sequence found in the 5' terminal regions of a variety of RNA species. The sequence starts with a CYTIDINE, which is followed by a stretch of 5 to 15 PYRIMIDINE NUCLEOTIDES. Messenger RNA that contains the 5' Terminal Oligo Pyrimidine tract is often referred to as 5' TOP mRNA. The sequence acts as a translational regulator and has been found in mRNAs for PEPTIDE ELONGATION FACTORS and RIBOSOMAL PROTEINS.
intein definition: self-calatytic protein splicing element; in-frame intervening sequence that disrupts a host gene and its protein product.
Inteins definition: The internal fragments of precursor proteins (INternal proTEINS) that are autocatalytically removed by PROTEIN SPLICING. The flanking fragments (EXTEINS) are ligated forming mature proteins. The nucleic acid sequences coding for inteins are considered to be MOBILE GENETIC ELEMENTS. Inteins are composed of self-splicing domains and an endonuclease domain which plays a role in the spread of the intein's genomic sequence. Mini-inteins are composed of the self-splicing domains only.
correlated observation sequences definition: Container for Observation Sequences (Observations whose values are contained in LIST<>'s) having values correlated with each other. Each contained Observation Sequence LIST<> must be the same length. Values in the LIST<>'s are correlated based on index. E.g. the values in position 2 in all the LIST<>'s are correlated. This is analogous to a table where each column is an Observation Sequence with a LIST<> of values, and each row in the table is a correlation between the columns. For example, a 12-lead ECG would contain 13 sequences: one sequence for time, and a sequence for each of the 12 leads.
Inverted Repeat Sequences definition: Copies of nucleic acid sequence that are arranged in opposing orientation. They may lie adjacent to each other (tandem) or be separated by some sequence that is not part of the repeat (hyphenated). They may be true palindromic repeats, i.e. read the same backwards as forward, or complementary which reads as the base complement in the opposite orientation. Complementary inverted repeats have the potential to form hairpin loop or stem-loop structures which results in cruciform structures (such as CRUCIFORM DNA) when the complementary inverted repeats occur in double stranded regions.
Chromosome Breakpoint Sequence definition: The specific sequence of DNA where CHROMOSOME BREAKS have occurred.
Sequence Inversion definition: The deletion and reinsertion of a segment of a nucleic acid sequence in the same place, but flipped in an opposite orientation.