The first one is a tutorial is at Washington University Sequencing Center, a well known sequencing facility in the US, that has colaborated in the sequencing of several genomes including the human genome, and C.elegans. Their tutorial depicts the technique of "classical shotgun" sequencing, which first requires creating a physical map of many overlaping large clones (YAC or BAC clones), then finding the tyling path with the smallest number of clones that fully covers the genome and last, sequencing each of those large clones using the shotgun approach. Once they have sequenced all those clones in the tyling path, they need to assemble them into a large single sequence (one for each chromosome) and if any gaps are left, they need to fill them as far as possible (some regions of repeated DNA are very difficult to sequence and to assemble).
This tutorial only covers the portion
related to sequencing
itself. When you display the entry page, try to follow the sequential
order of pages using the flowchart. If you use the text links at
the end of everypage, you will miss some pages.
The second tutorial is at Celera genomics, a private company that has been very controversial in the last years because of their differences with the public Human Genome Project. They also finished the fly's genome. Their sequencing process is a little different to that of the WashU Sequencing Center, which they claim it allows them to sequence an entire genome in much less time (they skip the physical map and do a complete genome shotgun sequence strategy).
Their tutorial is very simple and
is very graphical, but it requires the FLASH plugin and a computer with
sound. When you open the tutorial page, if you can't see it, download
the FLASH plugin, install it and come back to this page. Once you are
in the sequencing
tutorial page, click on "DNA Sequencing Fundamentals" and
then on "Sequencing Approaches (Shotgun sequencing)".
There are other items displayed which are unnecessary for our purpose,
but you are free to listen to. If you don't have sound capabilities
on your system, you can still see the images, but be patient because it
will appear to be SLOW.
When you are done, close the tutorial
pages, and then close this page, returning to the database readings.
(close this window)