Canadian Medical Guide > Biological Sciences > Biochemical Phenomena, Metabolism, and Nutrition > Biochemical Phenomena > Molecular Structure > Base Sequence Terms and Definitions

Base Sequence

Medical Definition:	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Guide Notes:	IM general only; coord with specific nucleic acid; do not confuse with BASE COMPOSITION: comp = what components & how many, sequ = order in which arranged; for base sequencing, use SEQUENCE ANALYSIS, DNA or SEQUENCE ANALYSIS, RNA; when to index with MOLEC
Also Called:	DNA Sequence,RNA Sequence
Previously Indexed:	Nucleotides/analysis (1966-1970),Polynucleotides (1966-1970),specific nucleic acid (1966-1970)

Base Sequence Categories.

	AT Rich Sequence - A nucleic acid sequence that contains an above average number of ADENINE and THYMINE bases.
	GC Rich Sequence - A nucleic acid sequence that contains an above average number of GUANINE and CYTOSINE bases.
	Matrix Attachment Regions - Regions of the CHROMATIN or DNA that bind to the NUCLEAR MATRIX. They are found in INTERGENIC DNA, especially flanking the 5' ends of genes or clusters of genes. Many of the regions that have been isolated contain a bipartite sequence motif called the MAR/SAR recognition signature sequence that binds to MATRIX ATTACHMENT REGION BINDING PROTEINS.
	Regulatory Sequences, Nucleic Acid - Nucleic acid sequences involved in regulating the expression of genes.
	Repetitive Sequences, Nucleic Acid - 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 occuring 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.

Base Sequence Medical Definitions and Terms

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