What is VNTR?
VNTR or Variable Number of Tandem Repeats are DNA sequences that are repeated at a given position. Repeats are grouped together and oriented in the same direction. Individual repeats can be added or removed by recombination errors. This creates alleles with a different number of repeats.
DNA fragments vary from person to person and are therefore useful in identifying individuals if there is room for crime or a paternity dispute. This is known as DNA fingerprinting.
Types of VNTR
These are highly repetitive DNA sequences and each DNA sequence contains several thousand base pairs. The satellite can measure up to 100 million base pairs. Satellites abound on the Y chromosome. This makes it easier for researchers to study paternal disease in mammals.
The density of DNA is a function of its base and sequence. Satellite DNA containing highly repetitive DNA has a lower density compared to the rest of the genome. Hence the name “satellite DNA” was coined.
- The satellite DNA is located in the centromeric and pericentromeric regions. regulates centromere activity.
- They contribute to the formation of heterochromatin.
- Satellite RNA transcripts are found in plants, vertebrates and invertebrates
Minisatellite
Each repeat in a small satellite varies from 9 base pairs to 100. This is a sequence of tandem repeats 500 to 300,000 base pairs long.
Small satellites associated with important aspects of the human genome such as gene regulation, transcription, and chromosomal fragile sites were identified and thus provided the first clues of highly diverse, highly allelic strains to study relationships.
Microsatellite
The repeats are very short, with 2-6 base pairs each. The entire sequence is between 10,000 and 100,000 base pairs long. They are therefore called short tandem repeats or simple tandem repeats.
They are commonly found in insect and plant chromosomes and in vertebrate euchromatin regions.
Microsatellites are important to population geneticists because of the variable replication rate among individuals of a population.
Microsatellite markers are inherited from both parents. Therefore, they are useful for genetic testing. A wide variety of morphological sites improves our ability for parentage analysis.
Microsatellites are unaffected by natural selection. However, they are affected by gene flow, genetic drift and mutation.
Importance of VNTR
- VNTRs are located on many chromosomes and vary in length in different individuals. Each variable is individual or contributes to parental identification.
- VNTRs are an important source of genetic RFLP marker used in genomic linkage analysis. A fashion model unique to each individual is developed by VNTR.
- VNTR has applications in forensic science, DNA fingerprinting, and other genetic and biological research.
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