Sunday, July 17, 2011
The case of "junk DNA" and why it shouldn't be called junk
Human DNA is made of roughly three billion pairs of nucleotides. In other words, each of our chromosomes contains a long string of A's, G's, T's and C's, and all together those strings form a word that's long three billion letters.
When the Human Genome Project started, scientists expected to find millions of coding genes. Coding genes are strings of DNA that contain the "instructions" on how to make proteins. When the project was completed, in 2003, they had found roughly twenty thousand coding genes. The surprise? Most of our DNA is not made of genes.
What is it made of, then?
It's been called many names: pseudogenes; junk DNA; non-coding DNA. Of all terms, "junk DNA" is the most unfortunate. Just because it doesn't have a function that we know of, it doesn't mean it's not important. And it doesn't mean it can't affect our lives.
In the next few weeks I'll make a case that "junk DNA" is indeed important.
It's part of our history, our heritage, and our future.
I will make my case using three concepts:
Picture: Lion's Mane Jellyfish, New England Aquarium, Boston. Canon 40D, exposure time 1/30, focal length 30mm.