The World of Genomics

Genomics is a study of the genomes of organisms.

It’s main task is to determine the entire sequence of DNA or the composition of the atoms that make up the DNA and
the chemical bonds between the DNA atoms. Knowledge of the DNA sequence has become an important part of biological research
but it is also of vital importance in other research disciplines including medicine, biotechnology and forensic.



The Human Genomics

The human Deoxyribonucleic acid (DNA) is the chemical compound that contains the instructions needed to develop and direct the activities in a human being. These DNA molecules are made up of two twisting, paired strands, often referred to as a double helix.

Each human DNA strand is made of four chemical units, called nucleotide bases, which comprise the genetic alphabet. The bases are adenine (A), thymine (T), guanine (G), and cytosine (C). Bases on opposite strands pair specifically: an A always pairs with a T; a C always pairs with a G. The order of the As, Ts, Cs and Gs determines the meaning of the information encoded in that part of the DNA molecule just as the order of letters determines the meaning of a word. Virtually every single cell in the human body contains a complete copy of the approximately 3 billion DNA base pairs, or letters, that make up the human genome.

With its four-letter language, DNA contains the information needed to build the entire human body. A gene traditionally refers to the unit of DNA that carries the instructions for making a specific protein or set of proteins. Each of the estimated 20,000 to 25,000 genes in the human genome codes for an average of three proteins.

DNA Sequencing

Sequencing is the process of determining the exact order of the bases in a strand of DNA. Because bases exist as pairs, and the identity of one of the bases in the pair determines the other member of the pair, researchers do not have to report both bases of the pair.

To assemble the sequence of all the bases in a large piece of DNA such as a gene, researchers need to read the sequence of overlapping segments. This allows the longer sequence to be assembled from shorter pieces, somewhat like putting together a linear jigsaw puzzle. In this process, each base has to be read not just once, but at least several times in the overlapping segments to ensure accuracy.

Researchers can use DNA sequencing to search for genetic variations and/or mutations that may play a role in the development or progression of a disease. The disease-causing change may be as small as the substitution, deletion, or addition of a single base pair or as large as a deletion of thousands of bases.

The Human Genome Project

The Human Genome Project, which was led at the National Institutes of Health (NIH) by the National Human Genome Research Institute, produced a very high-quality version of the human genome sequence that is freely available in public databases. That international project was successfully completed in April 2003, under budget and more than two years ahead of schedule.

Apart from genetics, diet, lifestyle and environmental exposures are the several other factors that contribute to people's risk of developing most common diseases. A deeper understanding of genetics will shed light on more than just hereditary risks by revealing the basic components of cells and, ultimately, explaining how all the various elements work together to affect the human body in both health and disease.