DNA Analysis: DNA Purification & PCR-based Analysis (original) (raw)

DNA profiling is an important forensic technique

DNA profiling is a forensic technique in criminal investigations, comparing the profile of crime suspects to DNA evidence to assess the likelihood of their involvement in a crime. It is also used in determining parenthood and in genealogical and medical research. DNA profiling is also used in the study of animal and plant populations in the fields of zoology, botany, and agriculture.

DNA fingerprinting-Science of Establishing Identity

Deoxyribonucleic acid (DNA) is the main constituent of the chromosomes of all organisms, and is found in the form of a double helix within the nucleus of every somatic cell and gives an individual a personal genetic blue print. Consequently, a small sample of human body cells can be decoded to reveal a pattern that is shared only by a genetically identical twin. The DNA of each individual does not change during his lifetime. This technique is commonly used in police investigations and is termed ‘DNA fingerprinting’- A search for TRUTH. DNA analysis first introduced into policing in 1986 when Dr. Alec Jeffereys of the University of Leicester assisted UK Police in investigation of potentially linked sexual assault coupled with murder of two young girls.DNA Technology provides a tool in the hands of police with a potential “genetic eyewitness”, thus links crime with criminal/s and regarded as the standard of excellence for the development of impartial, unbiased scientific evidence to ensure accuracy, transparency and fairness in criminal justice system. DNA Fingerprinting technique to use the highly variable polymorphic regions of DNA to identify individuals by preparing a profile.DNA typing is the most important advancement in the field of Forensic Science. It serves as a powerful forensic tool, not only because of its high level of discrimination among individuals, but also because it can be done with many sources of biological materials e.g. blood, blood stains, semen, seminal stains, tissues, bones, teeth, hair roots, etc. Indeed, the stability of DNA molecules allows genetic typing even from decomposed and/or fossilized materials. Hence exhumed bodies, partial fragmented materials from war victims, or even bones from mummified individuals had been tested to identify people through DNA typing

DNA FINGERPTINTING : A FORENSIC APPROACH

DNA analysis is one of the greatest technical achievement for crime investigation since the discovery of fingerprinting a century ago. Methods of DNA profiling tests conducted on biological evidence are certain to exclude an innocent suspect and link the guilty. When DNA profiling is done with appropriate care the result are highly reproducible and conclusive enough to prove the guilt or innocence of the suspect and link the guilty to crime. When DNA is done with appropriate care the results are highly reproducible and conclusive enough to prove the guilt or innocence of the suspect beyond reasonable doubt. DNA fingerprinting or profiles have broad application in forensic analysis such as paternity testing, murder, rape, individualization, etc. The conventional use of immunological and polymorphic enzyme system, work best in exclusion cases but chance of inclusion does not exceed above 99.7%. In DNA profiling the probability of identical pattern between the two randomly selected individuals is in order of 1 in 10 14 to 10 10 , keeping in mind the world population which is approximately 5x-10 16 thus the DNA profile can be consider if highly unique (except monozygotic twins) The objective of DNA laboratory is to help the police to solve the crime and also to help the judiciary to criminal justice. DNA Fingerprinting technique to use the highly variable polymorphic regions of DNA to identify individuals by preparing a profile. DNA typing / profiling was first described in 1985 by an English geneticist " Sir Alec Jeffreys ". DNA is present in every nucleated cell and is therefore present in all biological materials. DNA typing is the most important advancement in the field of Forensic Science. It serves as a powerful forensic tool, not only because of its high level of discrimination among individuals, but also because it can be done with many sources of biological materials e.g. blood, blood stains, semen, seminal stains, tissues, bones, teeth, hair roots, etc. Indeed, the stability of DNA molecules allows genetic typing even from decomposed and/or fossilized materials. Hence exhumed

DNA Profiling in Forensic Science

Encyclopedia of Life Sciences, 2001

Since 1985, DNA profiling in forensic science has rapidly evolved into an important technique that solves both major and minor crimes. A valuable innovation was the inception of the UK National DNA database that now comprises over 700 000 samples.

DNA Profiling Technologies in Forensic Analysis

International Journal of Human Genetics, 2004

The remarkable advances in DNA technologies over the past two decades have had an enormous impact on human identification, medical diagnosis, population genetics, understanding of evolution of species, wildlife management, characterization and unfolding the mysteries of antiquity of archaic specimens. This article presents an overview of the current technologies in the field of forensic genetics, their evolution and the emerging trends. DNA techniques have opened a new frontier in forensic analysis. Until 1985 all polymorphic immunological and biochemical markers employed to identify biological samples in criminal cases had limited applicability. The way to a new course of events was first paved by the introduction of minisatellites using multilocus probes (MLPs), providing incomparably higher discriminatory power. However, the procedures for multilocus typing were too arduous and required very large amounts of intact DNA which were usually not recovered from the difficult forensic biological specimens. This paved way for initiation of single locus probes (SLPs) in VNTR (variable number of tandem repeats) detection analysis. The advent of the polymerase chain reaction (PCR) was the turning point in the crucial issue of analytical efficiency of the DNA variants in the genome. Since then the field of molecular identification seems to have acquired a virtual unlimited power of analysis allowing experts to address even the most inaccessible sources of DNA. The first PCR amplification based DNA technique used in human identification was the reverse dot blot assay (HLADQA1 and PM typing), which was followed by short tandem repeat (STR) PCR multiplex analysis. Ease of amplification and automation are the salient features of STR analysis. Other contemporary DNA markers and techniques in vogue in forensic investigations include Y-STRs, mtDNA polymorphisms, RAPD and analysis of sequence variation in conserved mitochondrial genes for species identification. Single nucleotide polymorphisms (SNPs) analysis using single stranded conformational polymorphisms (SSCP) and micro array techniques are innovative additions in DNA field, throwing new light into the field of human identification and population studies. A brief discussion of these technologies, overview of their applications, their merits and demerits have been provided in the paper. National and international scenario on application of DNA methods, information on quality assurance programs and DNA databases have been dealt with for better comprehension of the advantages and limitations of DNA based technologies.

DNA Profiling in Forensic Science: A Review

Global Medical Genetics, 2021

DNA is present in most of the cells in our body, which is unique in each and every individual, and we leave a trail of it everywhere we go. This has become an advantage for forensic investigators who use DNA to draw conclusion in identification of victim and accused in crime scenes. This review describes the use of genetic markers in forensic investigation and their limitations.

Forensic DNA analysis in criminal investigations

Philippine Journal of Science, 2003

DNA analysis is a most powerful tool for human identification and has clear forensic applications in identity testing (crime scene and mass disaster investigations) and parentage determination. The development of forensic DNA technology in other countries and its potential to improve the Philippine criminal justice system are briefly discussed. The utility of forensic DNA testing in criminal investigations was highlighted using an actual criminal case wherein DNA evidence played a clear role in the resolution of the case.

DNA Technology and Police Investigations

Encyclopedia of Criminology and Criminal Justice, 2014

robin.williams@northumbria.ac.uk mattias.wienroth@northumbria.ac.uk SYNONYMS DNA profiling, DNA fingerprinting, Forensic Genetics, DNA Databasing OVERVIEW A forensic DNA profile is constructed by measuring highly polymorphic sequences of DNA in order to compare biological samples (especially blood, semen, skin cells, saliva, vaginal and nasal secretions, sweat and other human tissue) found at a crime scene with samples taken from known individuals and those found at other crime scenes. First introduced in the 1980's, forensic DNA profiling is increasingly important to police investigations and criminal prosecutions in a large number of cases. However, despite its acknowledged successes in many criminal jurisdictions, debate continues about the general utility of forensic DNA technology to criminal investigations; the significance of due process and human rights challenges to the increasingly routine uses of DNA databasing; and the socio-ethical acceptability of some recent innovations in forensic DNA analysis.