The use of Minisatellites in Forensic Science

Authors Avatar

Asya Zahra Husnain  The use of Minisatellites in Forensic Science

Introduction:

Forensic science is the branch of medicine that is concerned with the scientific investigation of the causes of injury and death in unexplained circumstances, particularly when criminal activity is suspected. Such investigations are carried out chiefly by pathologists at the request of the coroner, in conjunction with other experts and police investigators.

Forensic scientists focus on certain genetic sequences called “markers”. Here, the arrangement of genetic information is highly variable and particular to each person. A minisatellite (Dinucleotide repeat polymorphism’s) is one of these markers.(8) 

Minisatellites (variable number of tandem repeats, VNTRs) are particular to each individual. 99% of DNA is identical in everybody. 1% of DNA is different in each individual and thus allows one individual to be distinguished from another. Minisatellites are composed of core repeated sequences which are  9-80 base pairs in length. Another type of minisatellite that occurs is a hypervariable minisatellite. These are repeated sequences which are 9-24 base pairs in length. These highly polymorphic minisatellites share a common core sequence and appear near talomeres.(6) 

Microsatellites and Tetranucleotide / trinucleotide (STR’s) repeats are other markers which can be used. The tandemly repeated consensus sequences are only two to five bases long. Compared to minisatellites, the shorter repeat lengths of STR markers make them more compatible with use of the Polymerase chain reaction (PCR). PCR is a way to amplify minute amounts of DNA. This advantage has made them popular and useful markers for recent genetic maps.(3), (2).

Join now!

The variation in length of the minisatellites is the basis of DNA fingerprinting.

DNA fingerprinting is a way of identifying a person using the genetic material stored in the cells (particularly the nucleus within the cell where the DNA is found). DNA forensic analysis relies on one key characteristic of DNA: the configuration is the same in all cells of an individual. Altogether each person carries around 200,000 genes in each cell, comprising three billion “base pairs” -the chemical building blocks of DNA. Analysing all these base pairs and genes in order to identify an individual would be impossible, with current ...

This is a preview of the whole essay