71 134. During the hearing, an article published by the Central Forensic Science Laboratory, Kolkata40 was relied upon. The relevant extracts of the article are reproduced below: “Deoxyribonucleic acid (DNA} is genetic material present in the nuclei of cells of living organisms. An average human body is composed of about 100 trillion of cells. DNA is present in the nucleus of cell as double helix, supercoiled to form chromosomes along with Intercalated proteins. Twenty- three pairs of chromosomes present In each nucleated cells and an individual Inherits 23 chromosomes from mother and 23 from father transmitted through the ova and sperm respectively. At the time of each cell division, chromosomes replicate and one set goes to each daughter cell. All Information about Internal organisation, physical characteristics, and physiological functions of the body is encoded in DNA molecules in a language (sequence) of alphabets of four nucleotides or bases: Adenine (A), Guanine (G}, Thymine (T} and Cytosine (C) along with sugar- phosphate backbone. A human haploid cell contains 3 billion bases approx. All cells of the body have exactly same DNA but it varies from individual to Individual in the sequence of nucleotides. Mitochondrial DNA (mtDNA} found in large number of copies in the mitochondria is circular, double stranded, 16,569 base pair in length and shows maternal inheritance. It is particularly useful in the study of people related through the maternal line. Also being in large number of copies than nuclear DNA, it can be used in the analysis of degraded samples. Similarly, the Y chromosome shows paternal inheritance and is employed to trace the male lineage and resolve DNA from males in sexual assault mixtures. Only 0.1 % of DNA (about 3 million bases} differs from one person to another. Forensic DNA Scientists analyse only few variable regions to generate a DNA profile of an individual to compare with biological clue materials or control samples. ………………………………………… DNA Profiling Methodology DNA profile is generated from the body fluids, stains, and other biological specimen recovered from evidence and the results are compared with the results obtained from reference samples. Thus, a link among victim(s) and/or suspect(s) with one another or with crime scene can be established. DNA Profiling Is a complex process of analyses of some highly variable regions of DNA. The variable areas of DNA are termed Genetic Markers. The current genetic markers of choice for forensic purposes are Short Tandem Repeats (STRs). Analysis of a set of 15 STRs employing Automated DNA Sequencer gives a DNA Profile unique to an Individual (except monozygotic twin). Similarly, STRs present on Y chromosome (Y- STR) can also be used in sexual assault cases or determining paternal lineage. In cases of sexual assaults, Y-STRs are helpful in detection of male profile even in the presence of high level of female portion or in case of azoo11permic or vasectomized" male. Cases In which DNA had undergone 40 DNA profiling in Justice Delivery System, Central Forensic Science Laboratory, Directorate of Forensic Science, Kolkata (2007).