Bioinformatics

DNA Sequencing Techniques

Learn about the different types of techniques used to sequence DNA. We'll go over everything from maxam gilbert sequencing, sanger ddNTP sequencing to shotgun sequencing.Get a gist of what DNA sequencing is, what types of molecules can be sequenced, what breadth of information comes out of DNA sequencers, and the types of sequencing approaches available. Learn about the very first DNA sequencing technique pioneered by Alan Maxam and Walter Gilbert in 1976. Learn how Sanger sequencing works, which relies heavily on the chemical properties of dideoxynucleotides (ddNTPs). Also learn the pros and cons of the technique. Learn how scientists deal with the disadvantage of having short reads by utilizing a method known as primer walking. Learn how to get around the limitations of pyrosequencing by incorporating all four nucleotides in one run with reversible chain terminators. Learn the technique they used to sequence genomes that haven't been sequenced before (de novo) with the shotgun sequencing method.

Next-Generation Sequencing

Learn about how Next-Generation Sequencing techniques are used today to rapidly sequence billions of DNA base pairs for low costs. Learn what Next-Generation Sequencing (NGS) technology is, and what it means. Learn about emulsion PCR (ePCR), one of the PCR techniques used in next-generation sequencing. Thus far we have learned how to sequence DNA using sequencing by synthesis methods. Let's now learn how to sequence a DNA strand by ligation methods, which binds 8 to 9 bases at a time instead of just 1. Learn about the cheap, open-source polony sequencing works, created by George Church's group at Harvard Medical School. Learn about one of the very first second generation sequencing technologies. Pyrosequencing uses sequencing by synthesis and utilizes pyrophosphate as a means to detect whether a dXTP is present. Learn how the Ion Torrent machine works, and about the semiconductor sequencing technique. Learn how the ISFET sensor is used to as essentially a pH meter that detects when a dNTP is added to a growing strand of DNA. Learn about bridge PCR, another way DNA sequencers are amplifying their DNA in Next-Generation Sequencing devices. Learn how Illumina uses bridge PCR and sequencing-by-synthesis to sequence DNA in their Next-Generation Sequencing machines.