Performing Sequencing Reaction

Flow cell

The actual sequencing reaction is performed on a flow cell which is a special glass plate that is a little larger than a microscope slide. The surface of the flow cell is coated with short DNA sequences that recognize and bind to the DNA adapters we attached to the cDNA molecules during library preparation.

Because the RNA-seq library consists of many cDNA molecules floating in liquid, we can wash (or flow) the RNA-seq library over the surface of the flow cell. When we do this, many of the cDNA molecules in the library will stick to the flow cell's surface. The DNA sequencing module explains how the sequencing machine performs a small sequencing reaction at each location on the flow cell where a cDNA molecule is attached. By sequencing all the molecules attached to the flow cell at the same time, we can quickly read the sequences of the cDNA molecules in our library.

Illumina HiSeqX

Discussion Question

What is the name of the glass plate where we perform the actual sequencing reactions?