Both the public and private efforts to sequence the human genome relied on a technique developed by Fred Sanger (Sanger sequencing) in the late 1970s. View the animations to see the differences between the two methods and technique upon which they were based.
This animation shows how the human genome was sequenced using the 'hierarchical shotgun' method of the public Human Genome Project. All the base pairs in our DNA are represented as letters on pieces of paper.
(DNAi location: Genome > The Project > Putting it together > Animations > Hierarchical shotgun)
Duration: 1 minutes, 48 seconds
As represented by this huge stack of paper, the human genome contains more than three billion nucleotides or DNA letters. The first stage of the public Human Genome Project focused on identifying marker sequences or unique tags (shown here in yellow) at regular intervals throughout this "book of life." Once enough sequences were tagged, various blocks of the genome were allocated to different academic centers for sequencing.
To begin the sequencing process, several copies of a section of DNA (represented here as a page of text) are cleaved to produce smaller fragments. Although it looks fairly orderly, this step is small-scale "shotgun," which creates numerous random fragments. Each fragment is sequenced, then computer programs align the overlap between fragments to build up an entire page. Marker sequences (shown in yellow) help establish the order of pages in the "book of life." This methodical process produced huge amounts of data that have been used to virtually reassemble our genome. However, there are gaps. Repeat sequences are common in the human genome, so repeats from entirely different chromosome regions may be erroneously joined together. It will take many years to detect mismatches caused by the repeat sequences. Some regions, especially near the centromeres, may never be fully finished.
human genome project,shotgun method,base pairs,3d animation,genome sequencing,dna
Genome Sequencing: Shotgun technique.
Shotgun sequencing and dealing with repeat sections.
James Watson describes sequencing the human genome using markers and BACs, and Craig Venter explains using cDNA libraries, ESTs, and shotgun sequencing.
The DNA sequencing method developed by Fred Sanger forms the basis of automated "cycle" sequencing reactions today.
Craig Venter, leader of the private effort at Celera Genomics, speaks about his company's reliance on the public data for reassembly of the Celera sequence.
DNA is organized into 46 chromosomes including sex chromosomes, 3D animation
Eric Lander talks about whole genome shotgun.
Craig Venter, the leader of the private genome effort, talks about the "whole genome shotgun" technique that was used by Celera Genomics to sequence the human genome.
Eric Lander talks about analysis in public and private Human Genome Projects.
The public genome project aimed to sequence the entire genome in an ordered, methodical manner.