What happens inside the sequencer?

Once DNA has been extracted from the sample and prepared for sequencing, it will be entered into a next generation sequencing machine. But what happens inside the ‘black box’? How does the machine ‘read’ the genome sequence and convert it into something that scientists can understand?

This animation will take you ‘inside the sequencer’ to highlight how it produces a read of every single base of many multiple fragments of DNA simultaneously, using one particular type of technology as an example. The animation highlights how the process of DNA replication – in which the guanine base (G) is always paired with the complementary cytosine base (C), and the adenine base (A) is always paired with the complementary thymine base (T) – is highjacked by the sequencing process. During the sequencing process new strands of DNA are built using an existing strand as a template and as each new base is added to the strand, the sequencer can ‘take a snapshot’ of the new base and so produce a read of the DNA sequence. The animation visualises, and should help you to understand, the complex processes that take place inside the machine.