Difference Between Minisatellite and Microsatellite - NEET

The DNA sequences that repeatedly occur throughout the genome are referred to as repetitive DNA. It is a portion of the non-coding DNA that is dispersed across the euchromatin. Few base pairs to hundreds of base pairs may make up the repeating unit. The repeating unit is about 300 bp in size. Per genome, it can be repeated 10–105 times. Tandem and interspersed repeats are the two primary kinds of repetitive DNA. 

The genome contains two different types of repeating DNA: Microsatellites and Minisatellites. While minisatellites are mostly used for paternity testing because they are found in family groups, microsatellite DNA is primarily used for DNA fingerprinting purposes.

The majority of eukaryotes include repetitive DNA, which is either clustered or dispersed amongst the unique genes. This is one of the main differences between the genomes of prokaryotes and eukaryotes. 

There are Several Types of Repetitive DNA: 

(1) Single copy DNA, which contains the structural genes (protein-coding sequences),

(2) Families of DNA, in which one gene copies itself, and the repeats are distributed throughout the genome or located in small clusters (tandem repeats), and 

(3) Satellite DNA, which contains short nucleotide sequences repeated thousands of times. 

These repeats are frequently discovered grouped together close to the centromeres (i.e., the attachment points for the nuclear spindle fibres that move chromosomes during cell division).

What are Microsatellites?

A repeating sequence of 2–6 base pairs in the genome is known as a microsatellite. Microsatellites are also referred to as small tandem repeats since they are a subclass of tandem repeats that include short nucleotide sequences (STRs). Single nucleotide polymorphism refers to repeated single nucleotides (SNP). Microsatellite DNA is also found across the entire genome. Dinucleotide repeats can be found every 30,000 base pairs in the human genome.

Additionally, the genome's microsatellite region is extremely mutative. DNA slippage during replication is the primary way that mutations are acquired. Within families, distinct microsatellite sequences can be found. As a result, we use microsatellite analysis to determine paternity. Trinucleotide microsatellite repeat expansion also contributes to the development of serious human diseases like Huntington's disease and Fragile X syndrome. They are mostly found in vertebrate euchromatin regions and the chromosomes of insects and plants.

What are Minisatellites? 

A 10-100 base pair repeating sequence known as a minisatellite DNA can be found in the genome. The repeating unit in this instance is rather large and is referred to as a DNA motif. Variable number tandem repeats is another term for minisatellites (VNTRs). Each person has a unique distribution of VNTRs. A minisatellite's repeating unit contains a lot of GC.

Scientists employ minisatellites for DNA fingerprinting because of their extreme individual variability. During the linkage analysis, they also use minisatellites as genetic markers. Ras oncogene-associated cancer is a result of certain minisatellite DNA sequences. Minisatellites have been connected to chromosomal weak regions, imprinting, and gene control, among other things. These are the components of the human genome that are most crucial. They are the first highly polymorphic and multiallelic linkage study markers. The majority of the minisatellites have strong strand symmetry and high GC content.

Difference Between Minisatellite and Microsatellite

In contrast to minisatellites, a type of polymorphic DNA made up of repeat units up to about 100 nucleotides in length, microsatellites are a collection of brief repeated DNA sequences at a specific location on a chromosome that varies in number between individuals and can be used for genetic fingerprinting. The fundamental distinction between a microsatellite and a minisatellite is this.

• Tandem Repeats Type: Minisatellites are VNTRs, whereas STRs are microsatellites.

• Occurrence: Although minisatellites are more common at the ends of the genome, microsatellites are more common across the genome.

• The Repeating Unit's Size: A microsatellite's repeating unit is 2–6 base pairs in size, whereas a minisatellite's repeating unit is 10–100 base pairs.

• Repeats Per Genome Number: In the genome, microsatellites contain a specific repeating unit around 5-200 times, while minisatellites include a specific repeating unit 10-1,500 times.

• The Array's Size: Another distinction between microsatellites and minisatellites is the size of the array of repeating units, which in microsatellites ranges from 10 to 1,000 base pairs as opposed to 0.5 to 15 kilobytes in minisatellites.

• Array Complexity: While the array of minisatellites is primarily heterogeneous, that of microsatellites is primarily homogeneous.

Interesting Facts

• The eukaryotic genome contains two different types of highly repetitive DNA called microsatellites and minisatellites that are crucial for maintaining the genome's structure even though they have no specific function.

• Since the intergenic areas do not include these DNA sequences, they are non-coding DNA.

• Moreover, both of them can be applied to the identification of people.

• Some of them might be linked to certain illnesses.

Important Questions

1. What is a gene?

Ans: The fundamental genetic component transferred from parent to child is called a gene.

2. For what do genes code?

Ans: The majority of genes include the instructions required to create useful molecules called proteins.

Key Features

• The eukaryotic genome contains microsatellites which are 2–6 base pairs long repetitive sequences. They can be utilized for paternity testing and are found widely across the genome. 

• Minisatellites, on the other hand, are a class of repetitive DNA having repeated sequences that are 10–100 base pairs long. They can be utilized for DNA fingerprinting and are primarily found towards the ends of chromosomes.

• In the examination of the CsCl density gradient, they show up as narrow, dark bands.