After two decades of research that began with the Human Genome Project producing the first draft of the human genome sequence, researchers have successfully completed the entire, gap-free DNA (Deoxyribonucleic Acid) sequence consisting of roughly 3 billion bases.
WHAT IS GENOME ?
German botanist Hans Winkler coined the word “genome” in 1920, combining the word “gene” with the suffix “-ome,” meaning “complete set,” to describe the full DNA sequence contained within each cell. Researchers still use this word a century later to refer to the genetic material that makes up an organism. Genetic information are stored in special macromolecules called DNA in the form of base pairs . There are four nitrogenous base pairs whose combination determines a gene .
While every living organism has a genome, the size of that genome varies from species to species. An elephant uses the same form of genetic information as the grass it eats and the bacteria in its gut. But no two genomes look exactly alike. Some are short, like the genome of the insect-dwelling bacteria Nasuia deltocephalinicola with just 137 genes across 112,000 nucleotides. Some, like the 149 billion nucleotides of the flowering plant Paris japonica, are so long that it’s difficult to get a sense of how many genes are contained within.
The human genome contains roughly 3 billion nucleotides and just under 20,000 protein-coding genes – an estimated 1% of the genome’s total length. The remaining 99% is non-coding DNA sequences that don’t produce proteins. Some are regulatory components that work as a switchboard to control how other genes work. Others are pseudogenes, or genomic relics that have lost their ability to function.
And over half of the human genome is repetitive, with multiple copies of near-identical sequences.
THE HUMAN GENOME PROJECT
Human Genome project was started in 1990 with the aim of exploring all the genetic information that is stored in the chromosome of a human .
When the Human Genome Project first launched in 1990, technological limitations made it impossible to fully uncover repetitive regions in the genome
Human Genome project completion was announced in 2003 but it came with a catch as they were not able to put together all the genetic information in the genome .There were numerous unfulfilled regions that were to confusing to piece together at that time it had mapped only 92% of genes, with the rest remaining a mystery for nearly two decades due to technological limitations .
THE PROBLEM DURING 2003
These repetitive gap regions were like putting together a 1,000-piece puzzle of an overcast sky: When every piece looks the same, how do you know where one cloud starts and another ends? With near-identical overlapping stretches in many spots, fully sequencing the genome by piecemeal became unfeasible. Millions of nucleotides remained hidden in the the first iteration of the human genome.
With the increasing power of long-read DNA sequencing technology, geneticists are positioned to explore a new era of genomics, untangling complex repetitive sequences across populations and species for the first time. And a complete, gap-free human genome was completed only after two decades uncovering all the repetitive region , providing the first comprehensive view of our DNA blueprint Now, scientists have finished sequencing the other 8%, and the human genome has finally been fully sequenced on March 31 2022
It will solve many mystery and untangle many hidden treatment in the future . it will let us know how the evolution occurred , what are the basis of cure of genetic disease .