What is Genomics?

In 1920, H. Winkler coined the term genome to describe ‘the complete set of chromosomal and extra-chromosomal genes of an organism or virus’. In eukaryotes DNA is also present inside the mitochondria and chloroplasts (in plants only).

After a gap of 66 years, Thomas Roderick in 1986 first used the term genomics and described it as a scientific discipline of mapping, sequencing and analysing the genome. This definition is unclear but emphasises the systematic exploitation of genome information to answer several queries arising from biology or its related areas.

Now the number, location, size and organisation of all genes required to make up an organism can be known. Significance of genomics was substantially increased when the Human Genome Project was conceived of in 1987. Officially the Human Genome Project was started on October, 1990 in the U.S.A.

Genome Sequencing Projects :

Throughout the world, scientists were trying to sequence the genome completely of several organisms of important groups. The reasons of sequencing the genome are given below:

1. It provides knowledge of total number of all genes

2. It shows relationships between genes

3. It provides opportunities to exploit the sequence for desired experimentation

4. It provides all genetic information about the organisms

5. Genome sequences act as an archive of all genetic information

Research work on Human Genome Project was successfully completed only due to international collaboration involving 60 countries, 20 genome research centres and more than 1,000 scientists. Upto 1990, some laboratories sequenced 1,00,000 nucleotides.

Human Genome Project got assisted internationally arid significant information’s were generated. On June 26, 2000 the ‘working draft’ of human genome was completed. Announcement of completion of this draft captured the imagination of people across the world as man had walked on the moon. Human genome is large consisting of -3 x 10′ base pairs and a lot of repeated sequences. Scanning electron micrograph of human chromosomes.

The 3 billion characters in the DNA sequence that make up the human genome were translated into biologically meaningful information by using computer. This act gave birth to a new field called ‘Bioinformatics’. The field of genomics relies upon bioinformatics. It holds the key to unlock these data for the next generation of innovations.

Besides, complete whole genomic sequences of over 1,000 viruses, over 100 microbes and 9 eukaryotes are known. Hundreds of genome sequencing projects are going on in different parts of the world and many are being started.

Some of the completely sequenced genomes include phage X, HIV, E. coli (4.639xl0⁶ bp), Helicobacter pylori causing stomach cancer (1.67xl0⁶ bp), yeast Saccharomyces cerevisiae (12.1xl0⁶ bp), nematode worm Caenorhabditis elegans (100 x l0⁶ bp) and the fruitfully Drosophila melanogaster (160 x10⁶ bp).

Many other genomic sequencing projects are underway including plants, fish, etc. By the end 1999, 97% chromosome 22 (34.5 x 10⁶ bp) was sequenced.

In 1995, the completely sequenced genomes of the first two smaWest bacteria, Haemophilus influenza Rd and Mycoplasma genitalicum, were reported. In 1996, the first yeast Saccharomyces cerevisiae genome sequencing was completed. In 1997, sequencing of genomes of the two best studied bacteria, Escherichia coli and Bacillus subtitles was completed.

Several computer programmes were adopted for data analysis. To carry out sequence assembly, several new computer programmes could also be written.

Genome sequencing of many bacteria including those of medical and industrial importance, and from extremes of environment {e.g. volcano and deep sea vents) were determined at ‘The Institute of Genomics Research (TIGR), Maryland (U.S.A.). This institute was established by Craig Venter.

Genomics sequenced human and mouse genomes. The human genome having over 3 x 10⁹ bp also possesses repeated sequence. The presence of repeated sequence creates difficulty in sequence assembly. But it may be a little easier to assemble if the parts contain the genes.

With the start of 2000, genomes of 23 different unicellular (5 archaeal, 17 bacterial, and 1 eukaryotic organism(s) had been completely sequenced.