What is 'The Genome'

'The genome' is one of those phrases that gets thrown around a lot.  All species have a genome, but I'm just going to specifically talk about the human genome today.  You may have read in the news that the first draft of the Human Genome Project was published in 2000, and then may have read all about it again in 2003 when a further refined version was published.  It's still not really 'complete'.

So what do we mean when we talk about 'the human genome'?

In it's most basic form it's all the DNA that is found in a human.  Except, we're all slightly different from each other (I have blue eyes, you may have brown eyes), also within you your cells don't all have the same DNA - there will be slight mutations, lots of these won't do anything, but they're also the changes that can lead to cancer.  So when we talk about the genome, we really mean a sort of averaged version of the DNA found in a human - it's often referred to as a reference genome.

Except we usually also leave out the DNA found in mitochondria, because it doesn't quite count...

Okay, so when we talk about 'the human genome', we mean all the DNA in a human (averaged, with some left out), right?

Sort of.  That's the basic level of information, but just the DNA code on it's own isn't that much use to anyone.  So, we also include the annotation (other information that we can attach to it), such as:

Where are the genes?
What do those genes do?
What about DNA that tells the genes when to be on or off (promoters, Transcription Factors)?
What about other weird bits of DNA like transposons (I'll talk about these soon as it's what I'm really interested in)?

A fairly recent project (which you may have also heard about in the news) called the 1000 genome project aims to reduce some of the averaging that goes on with the human genome.  This project will allow us to look at differences between the genomes of different people and differences across different populations.  But it still won't be a complete map of all the differences in the human genome.

The $1000 genome project aims to provide people with their own genome for $1000 (does what it says on the tin!), it's not in a great state at the moment, but as genome sequencing get cheaper and easier we get further along the journey towards really understanding the human genome.