Question: what is a jumping gene

Richard Badge answered on 15 Jun 2011:

Hi sam12,

Always love this question…

I think that most people are happy with the idea that genes are found in our chromosomes and are made of DNA. The vast majority of genes stay put at one distinct “address” on a chromosome – this can be as general as on the short arm of the longest chromosome (chromosome 1 in humans), or very specific – mapping the human genome by DNA sequencing enable us to pin down genes to precise ranges of nucleotides (the gene mutated in cystic fibrosis lives at positions 117,120,017 to 117,308,716 on human chromosome 7.

Jumping genes move around – i.e. they can be found at lots of different addresses in our DNA, and the ones we work on are often different between people – you and I might have a different jumping gene at position 117,120,017 on our number seven chromosomes, for example.

The best guess for how these jumping genes work is that they are related to viruses (or even that they gave rise to viruses, but that’s another story). What we do know is that they have been moving around for millions of years in mammals genomes and building up to the point that just under half of your DNA is made of them… but we don’t think they have any use so we usually call them parasites.

Occasionally the jumping genes we work on do jump into a gene and break it, but this is very rare. Recently there has been some work that suggests they jump around more in cancer… this doesn’t mean that they cause cancer (although one case where they do is known) but having bits of DNA flying around and breaking genes probably does not help!

Richard