Friday, September 7, 2012

Highly detailed map of the human genome created

In 2003, scientists presented the first complete sequence of the human genome, comprising over 6 billion individual DNA building blocks. Of course, by just knowing the code, you know nothing about its function. That is why shortly after completing the code sequence, scientists started working on the interpretation of the genome. A project called Encode is devoted to unravelling the complete picture of the blueprint that our DNA forms for all life's building blocks. It is known that individual parts of the genetic code can function as genes, each providing the instructions for production of a single protein, but there are many other ways DNA can do its job. The Encode project has so far attributed a function to 80 percent of the genome, which is fairly impressive.

Genes are the most well-known parts of our DNA, and represent individual packets of information necessary to make proteins, that consequently form the building blocks of cells. Over the course of years, we have discovered many human genes and assigned functions to them. However, despite our genome having around 20.000 genes in total, the amount of code used comprised only 1 percent of the total genome. Large chunks of our DNA were originally considered to be 'junk', which means they fulfil no use. Scientists have now discovered that such non-coding parts of the DNA do have various functions.

In order to discover what these junk parts of our DNA are doing, the Encode project was set up. Over the course of years, scientists tried to assign attributes to these non-coding parts, in order to create an encyclopaedia of the human genome. So far, around 80 percent of the human genome has been accounted for, and aside from genes, many other functions were placed on the genomic map. These include promoter regions, which are parts of the DNA that certain molecules can bind to in order to promote the activity of adjacent genes. Around 70.000 promoter sites have been put on the map, as well as 400.000 enhancer sites, the latter affecting the transcription of genes over a longer 'distance'.

While the scientists working on Encode seem to be doing fine with delivering an encyclopaedia on the human genome, their work is not nearly done. Despite covering 80 percent of the genome, there are many more features hidden in our DNA, perhaps even things that we have not seen before. According to the researchers, only around 10 percent of the actual work is done. Additionally, there is a project underway that does about the same thing as Encode, but will provide much more in-depth details about the genomic features.

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