In a series of articles, we'll start with the very basics of DNA sequencing, and build our way up to the techniques that were used to complete the human genome. From there, we'll spend time on the current crop of "next-generation" sequencing hardware, before going on to examine some of the more exotic things that may be coming down the pipeline within the next few years in sequencing Technology.
When a cell divides and DNA needs to be replicated, the double helix is split, and enzymes called polymerases use each of the two halves as a template for an new opposing strand; the base pairing rules ensure that the copying is exact, except for rare errors. Historically, DNA sequencing has relied on the exact same process of copying DNA—in fact, the enzymes that make copies of DNA within a cell are so efficient that biologists have used a modified polymerase to perform DNA sequencing and DNA sequencing Technology .
The DNA polymerase, which isn't shown, is able to add additional nucleotides (a sugar + base combination) under two conditions: they're in the DNA sequencing form, with three phosphate groups in a row, and they base pair successfully with the complementary strand. As the red highlight indicates, the polymerase causes the hydroxyl group (OH) at the end of the existing strand to react with the DNA sequencing , linking the two together as part of the growing chain.
There are only two more secrets to DNA sequencing. First, you need to make sure every polymerase starts copying in the same place, otherwise you'll have a collection of molecules with two randomly located ends. This part is easy, since DNA polymerases can only add nucleotides to an existing strand in DNA sequencing . So, researchers can "prime" the polymerase by seeding the reaction with a short DNA molecule that base pairs with a known sequences that's next to the one you want to determine in DNA sequencing .
When a cell divides and DNA needs to be replicated, the double helix is split, and enzymes called polymerases use each of the two halves as a template for an new opposing strand; the base pairing rules ensure that the copying is exact, except for rare errors. Historically, DNA sequencing has relied on the exact same process of copying DNA—in fact, the enzymes that make copies of DNA within a cell are so efficient that biologists have used a modified polymerase to perform DNA sequencing and DNA sequencing Technology .
The DNA polymerase, which isn't shown, is able to add additional nucleotides (a sugar + base combination) under two conditions: they're in the DNA sequencing form, with three phosphate groups in a row, and they base pair successfully with the complementary strand. As the red highlight indicates, the polymerase causes the hydroxyl group (OH) at the end of the existing strand to react with the DNA sequencing , linking the two together as part of the growing chain.
There are only two more secrets to DNA sequencing. First, you need to make sure every polymerase starts copying in the same place, otherwise you'll have a collection of molecules with two randomly located ends. This part is easy, since DNA polymerases can only add nucleotides to an existing strand in DNA sequencing . So, researchers can "prime" the polymerase by seeding the reaction with a short DNA molecule that base pairs with a known sequences that's next to the one you want to determine in DNA sequencing .
