Question: what is junk DNA

Remsha Afzal answered on 16 Nov 2018:

Hi Michelle!!
Very important question!!!!
So a long time ago (in the 1960s-1970s haha), when biologists looked at human DNA, they saw that only a TINY part of DNA coded for proteins. Proteins were known to be the building blocks of our cells, important for so many of our body’s different functions.
BUT the scientists also saw that MOST of the DNA they looked at didn’t even code for proteins!! So what was the function of these billions of DNA letters that didn’t even code for proteins?? Because the scientists back then weren’t sure what this DNA did, they just termed anything that didn’t code for protein “junk DNA” because they thought its function was unknown or even pointless!
Only recently, scientists have started to finally realize just how important this “junk” DNA is. They found that a good bit of these “junk” regions actually contained gene “switches” that control when and where our genes can be turned on or off.
Like if you think about a radio, if it doesn’t have switches or buttons it cant do you much good can it? But if it has buttons for turning it on and off, or for turning the volume up and down, or changing the station, you can do so much with that radio. Its the same concept with our genes! They need to be activated in specific cells in controlled amounts to make the right proteins in the right amounts in the right cells! So these days we don’t call it junk DNA anymore. We call it ‘non-coding’ or ‘regulatory’ DNA 🙂 I know its a long answer but hope that helped!