Posted in Sequencing Technology and Methods

Nucleic Acid Fragmentation: Three Methods

An essential step in preparing total RNA or genomic DNA samples for sequencing is cutting them down into usable fragments. For Illumina instruments, the bridge amplification aspect of the sequencing process works best when these fragments are between 100 and 1000 nucleotides long, and quality is improved by using fragments within a narrow size range (ideally no more than 200bp spread). There are several different techniques for accomplishing this: nebulization, sonication, and enzymatic fragmentation.

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Posted in Biology Basics

DNA Replication in Eukaryotes: The Cast of Characters

dsDNA: The double-stranded DNA molecule that needs to be copied! It contains specific sequences called origins of replication where the molecule can begin to be unwound and copied.

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Posted in Sequencing Technology and Methods

Adapter Ligation

For a DNA fragment to be sequenced on an Illumina instrument, it first has to attach to the Illumina flow cell. The interior of the fluidics lane on each flow cell is printed, top and bottom, with a lawn of single-stranded oligonucleotides. All our DNA of interest needs to have is a complementary region on each end for clustering and sequencing to take place.

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