The goal

sequence a small fragment of your own genome.

Pick a primer set to target a particular gene fragment, such as a gene containing a known mutation (a single nucleotide polymorphism, or SNP), or look at a gene in another organism to learn about its genetic history and identify which species it comes from (DNA barcoding).

The plan

  • extract some of your genomic DNA from buccal cells
  • amplify a fragment of your genomic DNA using PCR
  • mail the DNA to our DNA sequencing center
  • register your sample at http://cofactorbio.com/claim
  • get your results in 2-5 days.

The details

Genomics 101

  • The human genome is a double helix formed by two complementary nucleotide chains
    • each human genome is broken into 23 pieces, called chromosomes
  • The genome is made up of four different nucleotides, adenine, cytosine, guanine, and thiamine. A-T and G=C can bind together- this is called “base pairing”.
    • because of base pairing, if you know the sequence of nucleotides on one chain of the double helix, you can infer the sequence of the complementary chain.
  • All of your body’s cells have a two complete copies of your genome (they are diploid)
    • (but: mature red blood cells do not have a nucleus or a genome, and reproductive cells only have one copy. They are haploid).
  • Each human genome is made up of around 3 billion base pairs. These encode around 20,000 genes.

Sequencing

  • Sequencing the first human genome took hundreds of scientists close to a decade and cost over 1 billion dollars (fact check).
  • Advances in sequencing technology (second-gen sequencing) have lowered the cost of genome-size sequencing
    • however, it still costs tens of thousands of dollars to sequence a human genome
  • Sanger sequencing, on the other hand, is an earlier sequencing technology that is very widely used. Sanger sequencing typically costs around $10 and is available as a service from a multitude of commercial sequencing companies. However:
    • Sanger sequencing requires a DNA to be relatively short in length (thousands of bases, or Kb, is ok), concentrated, and pure.
    • In other words, to use Sanger sequencing to sequence DNA, you must prepare billions of identical copies of the same short length of DNA you are interested in (fact check). Sanger sequencing will not work if all the copies of DNA that you prepare do not have the same sequence.

Polymerase Chain Reaction

  • The Polymerase Chain Reaction (PCR) can be used to make many copies of a desired DNA sequence. Amplifying a DNA sequence with PCR is one way to prepare DNA for Sanger Sequencing
  • PCR is accomplished with several special chemicals in a machine called a PCR thermocycler
  • We’ll get into the details below.