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How Sequencing Is Done


Animation of the JGI production sequencing process
(Flash, 30 minutes, 3.5 MB)

At JGI, we use whole-genome shotgun sequencing. This is a technique for determining the DNA sequence of a genome by randomly shearing the DNA, sequencing multiple fragments whose sequences overlap, and inferring the original sequence by reassembling the fragments. Three sizes of fragments are sequenced, 2-4 kb (kilobase, or 1000 bases), 8-10 kb, and 40 kb. This explanation follows the procedure for 2-4-kb fragments. Procedures for the other sizes are similar.

I.Library Creation

            1. Shearing of DNA

            2. Insertion of Fragments into a Plasmid

            3. Transformation

            4. Subcloning the Sheared Fragment

            5. Colony Picking

II.Production Sequencing

            6. Lysing the Cell

            7. Rolling-Circle Amplification

            8. Sequencing Chemistry

            9. Post-Sequencing-Reaction Cleanup

            10. Capillary Sequencing

III.Assembly and QA

            11. Assembly

            12. Quality Assessment