One Gene’s Junk is Another Gene’s Treasure

Those plastic bags Coles used to give out (or still do?), although terrible for the environment, were not complete junk — we re-used them as little bins around the house! Maybe you could re-purpose that half-finished can of pineapple chunks in a creative recipe. And kids just can‘t get enough of old packaging for their egg drop contest.

You say junk, he says parachute strap. Photo credit: Miki Fath via Unsplash

Utility is in the eye of the beholder, and it turns out our DNA worked this out long before we did.


You are at least 98% junk


We know that we are made up of DNA, and that DNA is organised into units called genes. While it is true that genes encode the instructions to produce our entire bodies — there is more to the story.

Scientists estimate that genes only make up around 1-2% of our DNA! So what is the rest of the DNA doing?

For years, scientists have labelled non-gene segments of DNA as “junk” DNA. Since no genes are present, we assume this DNA must have no interesting function. But just like a 5 year old can look at an egg carton like its gold, our DNA uses this “junk” for a higher purpose.


But the cool kind of junk


As we unravel the mysteries of the genome, we realise more than just genes can be excavated from the genomic gold mine. If anything, the genes are the boring part!

Okay, okay, so I’m admittedly biased because I research non-gene coding DNA. But let me explain why it is so cool.

Just like RNA, flour needs a bit of preprocessing. Photo credit: Erin Waynick via Unsplash

So say you wanna bake a cake.

What do you do?

  • You grab your recipe book off of the shelf
    (your genome)
  • Open it to the page containing the recipe
    you want (the gene of interest)
  • Then you follow the instructions to make
    your cake!

Now, I am definitely not this organised, but imagine that you get each ingredient, one by one, and place them along your bench top.

You are translating the instructions of the recipe to an intermediate form. An intermediate between your recipe book and a delicious, delicious cake.


We call this “transcription”. The process of transferring the information stored in DNA, into a similar molecule called RNA. And of course, the “protein product” in this analogy is the end product — the cake!



“Junk” with a purpose


What I find so fascinating about RNA is that most of the genome is actually transcribed! It is just that 98% of the flour ends up on the floor. Unlike the flour, however, RNA can go off and perform other functions. These “non-coding” RNA often have vital regulatory roles within a cell.

I work with what is called microRNA which, as the name suggests, are small little RNA molecules. These little guys have a role in inhibiting other genes, preventing them from producing the end product. This is kind of like finding little ants in your bag of sugar — you’re not going to be baking a cake today!

And of course half the fun of baking is getting creative! Taking the best aspects of multiple recipes, swapping ingredients in and out, and sharing recipes with other bakers.

Non-coding RNA come in all shapes and sizes. Some of them can promote the processing of a gene. Others might jumble up the genetic code. Or even modify other RNA. And just to make things even more confusing — RNA behave differently in different cell types!

We are always unraveling new functions for what we thought were well known molecules. If instead of a cake, the goal is to make a pizza, perhaps that is what your leftover pineapple chunks could be used for!

In other words, there are a wide range of non-coding RNA, which all play unique yet important roles in the miracle that is life.


We should retire the term “Junk”


This is still a fairly contentious issue.

Some scientists suggest that as much as 80% of the genome may have some sort of function. While other biologists estimate that merely 25% of the genome is functional.

Jenn Vargas Via Flickr

There is still SO much left to explore before scientists can decide how much of the genome is functional. Or even decide how we define “functional”. As far as I’m concerned, everything
functional appears non-functional until we uncover it’s function! But we do know one thing, it is about time to retire the term “junk” DNA.

We should keep an open mind.

You never know what weird and wonderful things your junk could be used for.



If you would like to learn more…

  • Here is a more in-depth explanation of how DNA transcribes into RNA, and then translates into protein.
  • An overview of the different types of non-coding DNA can be found here.
  • This paper discusses how we might be able to distinguish between “junk” and non-junk DNA.

15 Responses to “One Gene’s Junk is Another Gene’s Treasure”

  1. Thanks! I appreciate the feedback 🙂

  2. Ye Zheng says:

    Excellent post! I like the explanations of the transcription and translation, especailly regard microRNA as supervisors which protect sugar far away from ants. That’s an amazing and interesting idea. It seems find a way to explain some jargons. fabulous!

  3. Thank you! I’m glad you liked it. I’m surprised how well the analogy worked for RNA!

  4. Jing Deng says:

    Love how simple you presented these concepts! I initially thought about writing RNA interference, but then change my content because I couldn’t come up with an easily understood way to explain it. That’s why I love your post so much, it is such a great inspiration to me!

    Great work!

  5. Thanks Iman! Looking forward to yours, too 😉

  6. Iman Taleb says:

    oh wow! i loved the analogy! you’ve done a great job and i loved the flow as well! rock and roll and i can’t wait for your next blog!

  7. Thank you Daniel! I appreciate the comment 🙂

  8. Daniel Hutchinson says:

    Great post Holly. Really liked how the analogies made it so simple and easy to follow yet it never felt like information was left out.

  9. Stephanie Choo says:

    Hey Holly,
    In that case, sign me up to the ‘bake-off’. 😊

  10. Thankyou! And that’s a good point! I’m gradually realising that this analogy actually does well to explain a lot of the genome’s complexities. Like how photocopying your recipe is sort of like DNA replication?

  11. Stephanie Choo says:

    Thanks for an engaging article. Loved the baking analogu to explain transcription and translation. Admittedly, post-translational modifications (icing on the cake?) can also change how proteins produced by genes are expressed. It’s all rather confusing and you did a good job of explaining it.

  12. Thanks Connor! I appreciate the feedback!

  13. Great post, Holly! It engaged me from start to finish, and I loved the formatting of it – the use of dot points and the picture off to the side worked really well! I’ll definitely be looking at how I can improve the formatting of my next post thanks to this!

  14. Thanks Hannah! I’m glad I went with the cake analogy in the end – it’s something we can all relate to 😛

  15. Hannah says:

    Love you’re analogy! Such a great way to explain DNA -> RNA -> Protein as Recipe book -> Ingredients -> Cake!
    Also 100% agree that the term junk DNA should be retired 🙂