The main difference between microsatellite and minisatellite is that the repeating unit of a microsatellite consists of 2-6 base pairs while the repeating unit of a minisatellite consists of 10-100 base pairs. Furthermore, a microsatellite array contains 5-200 repeats while a minisatellite array contains 10-1,500 repeats.
Microsatellite and minisatellite are two types of repetitive DNA in the genome. The main use of microsatellite DNA is for DNA fingerprinting purposes while that of minisatellites is for paternity testing as they occur in family groups.
Key Areas Covered
1. What is Microsatellite
– Definition, Structure, Importance
2. What is Minisatellite
– Definition, Structure, Importance
3. What are the Similarities Between Microsatellite and Minisatellite
– Outline of Common Features
4. What is the Difference Between Microsatellite and Minisatellite
– Comparison of Key Differences
Key Terms
DNA Fingerprinting, Microsatellite, Minisatellite, Paternity Testing, Repetitive DNA
What is Microsatellite
A microsatellite is a repeating sequence of 2-6 base pairs in the genome. Since it is a type of tandem repeats with short sequences of nucleotides, microsatellites are also known as short tandem repeats (STRs). The repeats of single nucleotides are called single nucleotide polymorphism (SNP). Furthermore, microsatellites occur throughout the genome. In the human genome, the dinucleotide repeats occur in every 30, 000 base pairs.
Figure 1: Paternity Analysis
Moreover, microsatellites are a highly mutative region in the genome. The main method of acquiring mutations is through DNA slippage during replication. Unique microsatellite sequences occur within families. Therefore, we use the analysis of microsatellites for paternity testing. Furthermore, the extension of trinucleotide microsatellite repeats causes severe human disorders like Fragile X syndrome and Huntington’s disease.
What is a Minisatellite
Minisatellite is a repeating sequence of 10-100 base pairs in the genome. Here, the repeating unit is somewhat large and it is called a DNA motif. Another name for minisatellite is variable number tandem repeats (VNTRs). The number of VNTRs is highly variable among individuals. The repetitive unit of a minisatellite is GC rich.
Figure 2: Minisatellites
Due to the highly variable nature of minisatellites among individuals, scientists use them for DNA fingerprinting. They also use minisatellites as genetic markers during the linkage analysis. Some minisatellite sequences are involved in the formation of ras oncogene-associated cancer.
Similarities Between Microsatellite and Minisatellite
- Microsatellite and minisatellite are two types of highly repetitive DNA made up of tandem repeats in the eukaryotic genome.
- Although they have no assigned function in the genome, they are important in maintaining the structure of the genome.
- Also, these DNA sequences do not occur in the intergenic regions. Hence, they are non-coding DNA.
- Furthermore, both of them can be used in the identification of individuals.
- Some of them may be associated with diseases.
- They appear as small, dark bands in CsCl density gradient analysis.
Difference Between Microsatellite and Minisatellite
Definition
Microsatellite refers to a set of short repeated DNA sequences at a particular locus on a chromosome, which varies in number in different individuals and so can be used for genetic fingerprinting while minisatellite refers to a form of polymorphic DNA, comprising a variable number of tandem repeats, with repeat units of up to about 100 nucleotides in length. This is the basic difference between microsatellite and minisatellite.
Type of Tandem Repeats
Microsatellites are STRs while minisatellites are VNTRs.
Occurrence
In addition, microsatellites mainly occur throughout the genome while minisatellites mainly occur at the ends of the genome.
Size of the Repeating Unit
The size of the repeating unit of a microsatellite is 2-6 base pairs while the size of the repeating unit of a minisatellite is 10-100 base pairs. This is a major difference between microsatellite and minisatellite.
Number of Repeats per Genome
A particular repeating unit occurs about 5-200 times in the genome in microsatellites while a particular repeating unit occurs 10-1,500 times in minisatellites.
Size of the Array
Another difference between microsatellite and minisatellite is that the size of the array of repeating units is 10-1,000 base pairs in microsatellites while the size of the array of repeating units is 0.5-15 kb in microsatellites.
Complexity of Array
The array of microsatellites is mainly homogenous while the array of minisatellites is heterogeneous.
Conclusion
Microsatellite is a type of repetitive DNA in the eukaryotic genome with a 2-6 base pairs long repetitive sequences. They are widespread throughout the genome and can be used for paternity testing. On the other hand, minisatellite is a type of repetitive DNA with 10-100 base pairs long repetitive sequences. They mainly occur at the end of the chromosomes and can be used for DNA fingerprinting. Thus, the main difference between microsatellite and minisatellite is their structure and importance.
Reference:
1. Ramel, C. “Mini- and Microsatellites.” Environmental Health Perspectives105.Suppl 4 (1997): 781–789. Available Here
Image Courtesy:
1. “Stages of Gene Fingerprinting” By Sneptunebear16 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “VNTRexample” By Madelyndotson – Own work (CC BY-SA 4.0) via Commons Wikimedia
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