Grayce P. Storey
Human beings normally have 46 chromosomes, twenty-three (23) pairs in all but sex cells. Chromosomes are located in the nucleus of a cell. Chromosomes have thousands of genes which carry information for specific traits or inherited characteristics.
A gene is constructed of a segment of DNA (deoxyribonucleic acid) formed like a twisted ladder, known as the double helix. Each upright in the ladder consist of a chain of alternate sugar and phosphate units. The sugar is called deoxyribose.
Attached to each sugar unit is a chain of biochemical compound of a base. There are only four bases: adenine (A) , thimine (T), guanine (G), and cytosine (C). An individual gene may have from a thousand to several hundred thousand bases. The bases protrude from the sugar phosphate chains to form the rungs of the double helix ladder. The sequence of bases along the sugar phosphate chains is called the genetic code and the genetic code dictates to the other chemicals what to do.
When the DNA ladder breaks apart and the exposed bases read off in groups of three triplets to form a carrier substance, the process is known as messenger RNA (ribonucleicacid).
DNA in the nucleus of cells makes up the cells’ chromosomes. These are divided into genes which determine physical characteristics. Genes provide the blueprint for constructing a person. Genes are composed of DNA located in the nucleus.
DNA Fingerprinting
Most genes are identical or very similar from human to human. However, there are areas on or between the genome that are highly variable and unique for each individual. It is because of these differences the technique called ‘DNA fingerprinting‘ could be developed. The DNA fingerprinting technique produces a unique genetic map or ‘fingerprint‘ for each individual. Genetic fingerprinting is based on the unique DNA profile of an individual and has nothing at all to do with fingerprints.
DNA fingerprinting was developed and refined in the 1980’s and can prove valuable for linking criminals to a crime and for freeing innocent persons.
The procedure in making a genetic fingerprint is as follows. The researchers must isolate the target area of DNA and treat it with a combination of proteins called restriction enzymes. Since the target DNA is different from site to site, it may not split at all. The result is a combination of fragments of lengths. The fragments are eventually separated by lengths on a special piece of paper. They form a pattern which looks like the bar code used for identification of products in the supermarket. Crime lab technician can isolate DNA evidence to produce a genetic fingerprint to be compared with that obtained from a suspect. A very small amount of DNA, equal to that in a single hair, can be used to create the necessary fingerprint. A small amount of DNA can be converted into larger amounts through a process known as polymerase chain reaction, or PCR.