Genome

Genome the entire genetic information of a living organism is called its genome.All of the hereditary information that is required for the creation and maintenance of life and reproduction are contained within a genome. In humans, a complete copy of the genome is present in the majority of the cells of the body. The genome consists of both the coding and the noncoding DNA, along with chloroplast DNA and mitochondrial DNA. The human genome includes both nuclear and mitochondrial DNA. On the contrary, ribonucleic acid (RNA) viruses, consist of an RNA genome. In 1990, the Human Genome Project (HGP) was conducted to sequence the human genome and identify the genes it contains. It was an international research effort. When HGP was started, it was estimated that the human genome would consist of 50,000 to 140,000 genes. It is now known that roughly 3 billion base pairs and 20,500 genes are present in the human genome. The complete human sequence came out in 2003 (except 1% due to limitations in current research technology). More than 1,800 disease genes have been identified from the findings of HGP. Different species have different genome sizes. The genomes of invertebrates are small, therefore, the number of transposable elements is also small within them. On the other hand, the genomes of fish and Amphibians are intermediate in size. Sometimes even though two organisms are very distantly related, small parts of their genome share a high level of similarity which can be explained by horizontal gene transfer. [Tahirah Yasmin]