Scientists have fully sequenced the human genome for the first time—something that has been a scientific goal for decades.
During sequencing, the DNA of an organism is chopped up, read, and then re-assembled. Sequencing a genome can be thought of as something similar to putting together a complicated puzzle.
A large international effort to sequence the human genome, the Human Genome Project, was launched in 1990 and concluded in 2003. The project was able to sequence 92 percent of the human genome, with 8 percent still missing.
This missing eight percent consisted of chunks of DNA with highly repetitive sequences, like having identical puzzle pieces. This made it difficult to reassemble them correctly.
Scientists have now been able to do just that thanks to years of improvements in gene-sequencing technology and by studying one particular rare set of cells.
Usually, studying genomes is difficult because most cells contain two genomes—one from the father and one from the mother—which can complicate things.
However, the scientists behind the recent breakthrough made use of a particular set of cells being researched at the University of Pittsburgh that, due to a rare glitch in their development, had two copies of the father's DNA and none of the mother's.
Erich Jarvis, a Rockefeller University neurogeneticist who was part of the work, said in a Howard Hughes Medical Institute press release that the cell line "is what made this genome assembly possible."
Rajiv McCoy, an assistant professor in the Department of Biology at Johns Hopkins University, said in a university press release: "Opening up these new parts of the genome, we think there will be genetic variation contributing to many different traits and disease risk."
Dr. Eric Green, director of the National Human Genome Research Institute, said in a press release: "Generating a truly complete human genome sequence represents an incredible scientific achievement, providing the first comprehensive view of our DNA blueprint."
What is a genome?
A genome is a set of instructions for creating an organism, from a plant to a human.
All living things have a genome, and genomes are written inside DNA—around 3.2 billion letters for a human. The code is determined by the order of four chemicals called nucleotide bases: adenine, cytosine, guanine and thymine, or A, C, G and T for short, which make up DNA.
This four-letter language contains the information needed to build the entire human body. Sequencing means determining the exact order of these letters in a strand of DNA.
DNA has the famous double helix shape. Strands of DNA together form larger structures called chromosomes, which are stored within the nucleus of cells.
The sections of DNA within chromosomes are called genes, and these genes contain instructions that tell cells to make proteins. These instructions determine the features of individuals, including height, eye color, and hair color.
Genes should therefore not be confused with genomes. Genes form part of the genome, and there are around 20,000 genes within it.
Uncommon Knowledge
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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
