I recently listened to an amazing podcast titled “From Junk DNA to an RNA Revolution” by Bio Eats World, featuring Dr. Rick Young (an MIT professor focusing on gene regulation). This podcast gave amazing background on how and why this “junk” DNA terminology came about, and why we were so wrong!
The podcast gives various analogies of musical pieces throughout the discussion of junk DNA. In a sense, the works of junk DNA define the symphony of our lives!
We know from our grade school the central dogma of biology which is that DNA makes RNA and RNAs make proteins. Everything that does not make protein was called “junk” DNA. We now know that this is not true (spoiler alert!). The so-called junk DNA has some of the most important roles in biology. Arguably just as important as the genes that make proteins.
The proteins that are created by our bodies are regulated through transcription factors that sit on top of promotor sequences, which are non-coding sequences. The image below illustrates this mechanism.
These transcription factors determine whether the RNA polymerase binds to the protein and starts transcription or whether it is blocked off from the transcription of a certain protein. Enhances are the sequences that activate transcription and silencers are the sequences that deactivate the transcription of a certain protein.
The regulation of proteins is not the only function of these non-coding regions in the genome. There are an array of other functions. One such function is to help the protein transcription process. The transfer RNA that holds the amino-acid during transcription and the ribosomal RNA that carries out the overall transcription are all created from the non-coding regions of the genome.
For more, check out the podcast!
The lac operon (article). (n.d.). Khan Academy. Retrieved February 10, 2021, from https://www.khanacademy.org/science/ap-biology/gene-expression-and-regulation/regulation-of-gene-expression-and-cell-specialization/a/the-lac-operon
What is noncoding DNA?: MedlinePlus Genetics. (n.d.). Retrieved February 10, 2021, from https://medlineplus.gov/genetics/understanding/basics/noncodingdna/