Microsatellites in non-coding regions may not have any specific function, and therefore might not be selected against this allows them to accumulate mutations unhindered over the generations and gives rise to variability that can be used for DNA fingerprinting and identification purposes. Many are located in non-coding parts of the human genome and therefore do not produce proteins, but they can also be located in regulatory regions and coding regions. The human genome for example contains 50,000–100,000 dinucleotide microsatellites, and lesser numbers of tri-, tetra- and pentanucleotide microsatellites. Microsatellites are distributed throughout the genome. Most eukaryotes have microsatellites, with the notable exception of some yeast species. Repeat units of four and five nucleotides are referred to as tetra- and pentanucleotide motifs, respectively. For example, the sequence TATATATATA is a dinucleotide microsatellite, and GTCGTCGTCGTCGTC is a trinucleotide microsatellite (with A being Adenine, G Guanine, C Cytosine, and T Thymine). adjacent) DNA motifs that range in length from one to six or up to ten nucleotides (the exact definition and delineation to the longer minisatellites varies from author to author), and are typically repeated 5–50 times. Structures, locations, and functions Ī microsatellite is a tract of tandemly repeated (i.e. 1991), and of the Auschwitz concentration camp doctor Josef Mengele who escaped to South America following World War II (Jeffreys et al. Prominent early applications include the identifications by microsatellite genotyping of the eight-year-old skeletal remains of a British murder victim (Hagelberg et al. The increasing availability of DNA amplification by PCR at the beginning of the 1990s triggered a large number of studies using the amplification of microsatellites as genetic markers for forensic medicine, for paternity testing, and for positional cloning to find the gene underlying a trait or disease. The name "satellite" DNA refers to the early observation that centrifugation of genomic DNA in a test tube separates a prominent layer of bulk DNA from accompanying "satellite" layers of repetitive DNA. Microsatellites are also used in population genetics to measure levels of relatedness between subspecies, groups and individuals.Īlthough the first microsatellite was characterised in 1984 at the University of Leicester by Weller, Jeffreys and colleagues as a polymorphic GGAT repeat in the human myoglobin gene, the term "microsatellite" was introduced later, in 1989, by Litt and Luty. They are also used in genetic linkage analysis to locate a gene or a mutation responsible for a given trait or disease. They are widely used for DNA profiling in cancer diagnosis, in kinship analysis (especially paternity testing) and in forensic identification. Microsatellites and their longer cousins, the minisatellites, together are classified as VNTR (variable number of tandem repeats) DNA. Microsatellites are often referred to as short tandem repeats ( STRs) by forensic geneticists and in genetic genealogy, or as simple sequence repeats ( SSRs) by plant geneticists. They have a higher mutation rate than other areas of DNA leading to high genetic diversity.
Microsatellites occur at thousands of locations within an organism's genome. For small orbiting spacecraft, see Microsatellite (spaceflight).Ī microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Human sequence polymorphisms affect many base pairs large blocks of repeated sequences may inverted, deleted, or duplicated from one individual to another long interspersed nucleotide sequences (LINES)=highly repeated sequences, 6-8 kbp, that contain RNA polymerase promoter s and open reading frames related RT'ase of retroviruses>500,000 of these LINE-1 (L10 elements (15% of human genome) short interspersed nucleotide sequences (SINES)= scattered over genome, 0.This article is about the DNA sequence.
0 kommentar(er)
