Chromosome DNA molecules contain "recipes" for making all the proteins in the cell. Each "recipe" is a gene.
Therefore, the gene is a nucleotide sequence of the DNA that can be transcribed in a version of RNA and consequently translated into a protein.
A chromosome is comparable to a protein cookbook, and the nucleus of a human cell is comparable to a 46-volume library that contains the complete recipe for all of the individual's proteins. The complete set of genes of a species, with the information to make the thousands of protein types needed for life, is called the genome. Today, thanks to modern gene identification techniques, scientists have mapped the human genome through the Human Genome Project.
Human Genome Project
O Human Genome Project (PGH) aimed to map the human genome and identify all nucleotides that compose it. It was a worldwide effort to decipher the genome. Following the initiative of the National Institutes of Health (NIH) In the United States, hundreds of laboratories around the world have joined the task of sequencing, one by one, the genes that encode human body proteins as well as those non-gene DNA sequences. Developing country laboratories also participated in the venture to train qualified genomics workforce.
For sequencing a gene, it must first be amplified in a polymerase chain reaction, and then cloned into bacteria. After sufficient DNA has been obtained, a new chain reaction (PCR) is performed, this time using dideoxyribonucleotides labeled with fluorophores for sequence determination.
The project was founded in 1990, funded by $ 3 million from the US Department of Energy and the US National Institutes of Health, and was due for 15 years.
Due to the great cooperation of the international scientific community, associated with advances in the field of bioinformatics and information technologies, a first draft of the genome was announced on June 26, 2000, two years ahead of schedule.
On April 14, 2003, a joint press release announced that the project was successfully completed, with sequencing of 99% of the human genome to 99.99% accuracy.
The project's work was completed in 2003. With the technology of the time, it was estimated that all genes (around 25,000) had been sequenced. It should be remembered that not all human DNA has been sequenced. Current estimates conclude that only about 2% of human genetic material is made up of genes, while most appear to contain no instructions for protein formation, and probably exist for structural reasons. Very little of this most genetic material has its known sequence.
Due to technological limitations, parts of the DNA that have many nitrogen base repeats have not yet been fully sequenced. Such parts include, for example, the chromosome centromeres and telomeres.
Of all genes that have their sequence determined, approximately 50% code for proteins of known function.
Despite these gaps, genome completion is already facilitating the development of much more potent drugs as well as the understanding of several human genetic diseases.