ABSTRACT
Rory M.Hope Department of Genetics, University of Adelaide, GPO Box 498, Adelaide, South Australia, 5000
1.1 INTRODUCTION
We commence life as a single celled zygote, a fertilized egg about 0.1 mm in diameter and weighing less than 1 µg. Replication of this cell, and subsequent differentiation, give rise to a large diversity of specialized tissues, culminating in an incredibly complex yet exquisitely coordinated human adult consisting of more than 1014 cells and weighing about 70 kg. The bulk of the cells in such an organism (the somatic cells) are mortal and do not directly contribute to future generations. In a sense, immortality is achieved by transmission of genetic material to future generations via successful reproduction. The reproductive cells (gametes) retain the potential, when combined with a gamete supplied by the opposite sex, for repeating the whole course of development from zygote to adult. The numerous biological ‘instructions’ that enable these developmental and functional processes to occur are encoded in the molecular configuration of the chemical of heredity, deoxyribonucleic acid (DNA) which, together with protein, constitute the 23 pairs of chromosomes in each somatic cell. Some DNA also occurs in the mitochondria, cellular organelles concerned with the production and chemical storage of energy. Thus it is to the chromosomal and mitochondrial DNA molecules that we must look for answers to what are probably amongst the most fascinating questions about life: how is biological information encoded in DNA, how is it transmitted from cell to cell and from generation to generation, and how is the expression of this information regulated in time and space? The more modest aims of forensic science, however, are concerned with developing reliable methods for establishing identity based on naturally occurring differences between individuals. Therefore, questions of direct relevance to forensic science are: what genetic differences exist between the DNA of an individual and between the individuals of a population, and how can these differences be utilized to advantage in forensic analyses?
