DNA Sequencing


Did you know that your genome contains about six billion individual building blocks - and that we can now read the order of all those building blocks in about a day and for about $1000? Leaps in technology since the Human Genome Project have enabled remarkable genomics-based advances in medicine, agriculture, forensics, and our understanding of evolution.

Our genome (that is, our DNA "blueprint") - and in fact the genomes of all life forms on earth - are made of four chemical "bases" strung together in varying orders. To study the exact order (or sequence) of someone's DNA, researchers follow three major steps: (1) purify and copy the DNA; (2) read the sequence; and (3) compare to other sequences.

First they use chemical methods to purify, then, for some menthods, "amplify" the DNA in the sample - that means they copy small parts of the sample to reach high enough levels for measuring. The amplification step makes it possible to do DNA testing from very small starting amounts, like those in forensic samples or ancient bones. Then, different methods can be used to determine the order of each base in the DNA sample. Finally, they use computers to compare the sequence of the DNA to a reference sequence (for example, of the human genome), in order to see if there are any differences in the order of the bases.

Technology Advances Since The Human Genome Project

The Human Genome Project opened the door to vast improvements in three major areas:

  • The methods used to amplify and sequence DNA, including a million-fold reduction in the cost for sequencing a human genome.
  • Continually improving the accuracy of the reference "human genome sequences" that everyone can use for comparing newly generated human genome sequences.
  • Powerful new computer-based methods for analyzing and comparing many human genome sequences.

As a result, we now have multiple methods for sequencing DNA quickly and inexpensively (see videos in resource section below), and we have the computational ability to compare thousands of genomes at once.

DNA Sequencing Has Gone Mobile and Into Space

When the Human Genome Project officially started in 1990, no one knew that it would lead to the generation of over $1 trillion in economic return and the creation of hundreds of thousands of jobs. It brought together scientists from all over the world. In 2016, genomics went beyond this world! Dr. Kathleen "Kate" Rubins became the first person to sequence DNA in space. She used a hand-held instrument to sequence a DNA sample sent from earth, showing that DNA sequencing can be performed in space. In December 2017, fellow astronaut Dr. Peggy Whitson became the first person to sequence microbes brought from earth to the International Space Station itself. Adding this technology to the space station can bring the same advances in medicine and science to space exploration.

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