Everyone has genes that are referred to as junk genes; actually nearly half of our genes are junk genes. Junk genes are just sequences of our genome that scientists can not discern. Some of these junk genes do have a purpose and scientists just have not figured out what it is yet. Others are truly junk and do not code for anything. These will be the genes I am referring to as junk in the rest of this post. The current theory to explain the waste in our genome is that junk genes are viruses inserted throughout the evolution of the mammalian genome that are missing a piece of biological machinery to be transcribed. These viruses are essentially stuck in our genome not helping or hurting us. But are these junk genes really just junk?
Humans share 99% of our DNA with mice. Humans and mice have 99% equivalent DNA. This is a staggeringly high amount for how different we are as organisms, but this just looks at what genes are shared serve the same purpose and not what genes are expressed. The junk genes in our system are now believed to play some role in the expression of genes through human evolution. Junk genes can be transposons, or genes that can hop around in our genome from one spot to another. Sometimes this jumping can turn on or off gene expression in cells. If it is a helpful change the cell can thrive and the organism will hopefully pass on the improved cells. If it is a detrimental jump the cell will probably die and stop the genetic flaw. The recent study done on this idea of jumping genes aided scientists in the explanation of evolution but more importantly has made a step forward in being able to differentiate stem cells down their different paths.
What does it mean, looks at what genes are shared and not what genes are expressed? I've researched DNA similarities and no matter what the comparing method, I never saw a 99% similarity for mice/humans.
ReplyDeleteMany of our genes are not expressed in our phenotype i.e. if these genes were changed there would be no noticeable difference outside of our genome. We share many genes with mice that they express and we do not or vise versa. And as far as 99% here are a few sources that I used.
ReplyDeletehttp://articles.cnn.com/2002-12-04/tech/coolsc.coolsc.mousegenome_1_human-genome-new-human-genes-genes-that-cause-disease?_s=PM:TECH
http://news.bbc.co.uk/2/hi/science/nature/2536501.stm
But after some further digging I discovered the study that these articles are based on states that 99% of human and mouse genes are equivalent. I don't know if that is the same as shared or not.
I personally really like the photograph used for this post. Did you make that yourself or just found it on the internet? It fits really well with the post. It seems kind of weird to think that there are pointless 'junk' genes in our body. How is it possible to distinguish between the genes that have purpose but scientists haven't figured out what that is yet and genes that do not code for anything?
ReplyDeleteScientist use mice and other organisms to find the functionality of bits of our genome. Scientist knock out little bits of the mice genome and see what if anything changes. If they can not find any changes they consider that part of the genome to be junk genes. So I do not believe there is a way of saying what is truly junk and what has an unknown effect.
ReplyDeleteMichael's questions were the same as mine--I think I'm misunderstanding some of the terminology here. Clarification would be appreciated.
ReplyDeleteI do like that you note the changes you've made by scripting through--well done!