Question

What is satellite DNA in a genome? Explain their role in DNA fingerprinting.

Answer 1

DNA is the heredity basic of life as it contains all the information related to the organism. The DNA is present in the form of sets which includes all the different genes and this is known as the genome. The genome contains all the vital information regarding the organism.

Complete answer:
Satellite DNA is a non-coding DNA that does not encode the protein. DNA is mainly noticed in heterochromatin or the tightly packed regions of chromosomes in centromeres, telomeres. Sometimes it is also found in the euchromatin region or active region of the genome. Satellite DNA is made up of too large classification of tandemly repeating or arranged one behind one. The tandem repetitions in the DNA occur if a pattern of one or few nucleotides are repeated with adjacently placed. They are repetitive non-coding DNA.
Satellite DNA or sat DNA can be noticed in specific heterochromatin-rich chromosomal regions. This type of DNA builds vital formation such as functional centromeres and is also scattered within euchromatin. Though they form critical chromosomal structures, there are many variables of sat DNAs that are researched among species due to their high turnover rates.
Satellite DNA represents the process of repetitions of a short DNA sequence that has the tendency to produce a different frequency of the bases adenine, guanine, cytosine and thymine. They possess a different density from bulk DNA. When the genomic DNA is separated on a density gradient, a second or satellite band is formed. The sequences with a greater ratio of A+T show a lower density and the sequence with a greater ratio of G+C presents a higher density as compared to the bulk of genomic DNA.
Satellite DNA is classified into two types which are minisatellites and microsatellites and their characteristic helps to identify between two samples as DNA is polymorphic. The repeats of DNA can be as small as one to six base pairs long. This short tandem repeat will be called microsatellite and when DNA repeats are as long as ten to sixty base pairs long then these longer tandem repeats will be called as minisatellites.
The short sequences of DNA found in satellite DNA vary from individual to individual. The variations occurring in the length and sequence of satellite DNA are very unique to each individual. This property of uniqueness can be utilized to identify each individual based on their DNA map. The human genome is known to possess highly repetitive sequences of less than ten base pairs long or microsatellite DNA. These sequences are relatively uniform within the related species. They also reflect variability among the closely related species. The polymorphic nature of DNA is useful in creating DNA profiles of individuals. This technique is employed in DNA fingerprinting. It is massively applied in forensic sciences. This technique is used to identify criminals, perform paternity tests, and diagnose genetic disorders.

Note: Satellite DNA is composed of very large arrays of tandemly repeated DNA which means a single sequence of DNA is repeated many times over side by side. They are non-coding DNA in nature. Satellite DNA is the major ingredient to functional centromeres and builds the main structure of heterochromatin. They hold highly repetitive DNA. The major characteristic of satellite DNA is its uniqueness or the variation between individuals. For these features, it is used in DNA fingerprinting