Biotechnology

Junk DNA: Not So Junk After All!

Sep 23, 2012 By Deepa Gopal

Courtesy The Telegraph

Have you heard people say "Oh, it's all in the genes!" They may be referring to physical traits such as your eye color that you have inherited from one of your parents or grandparents. Genes, as you know, are passed down from one generation to next, and influence how we look, act and even the diseases we may be prone to.
When the human genome -- the entire genetic sequence that makes us what we are, was mapped out in 2001, it generated a lot of excitement (read our previous article here). We now knew exactly which genes controlled what features, and where these genes were located on the thread-like structures called chromosomes inside our body cells. Sounds great, doesn't it..
.. but there was a dilemma

Humans have 23 pairs of chromosomes; Gene Chromosome = Genome

You see, scientists had identified 21,000 genes that make up our entire genetic sequence. These genes produce enzymes and proteins that keep our body functioning. However, chromosomes have tons of DNA (DeoxyriboNucleic Acid) which are not part of the active genes. We had only understood 3% of all the DNA in the human genome. What was the purpose of the 97% of unused DNA? Scientists had no logical explanation and they called it Junk DNA.
The ENCODE project, led by 400 scientists from all over the world, has been trying to shed light on this junk DNA. Recently they announced a breakthrough. These seemingly unused DNA are actually the main control centers (or switches) that control how our genes work. Scientists have discovered 4 million such gene switches in the junk DNA, which decide which genes to turn on in which cells, and how much protein and enzymes the genes should produce.
Why is this important?
We can finally explain how cells that look the same to start out with in an embryo, change to become liver cells or brain cells? Groups of gene switches work together to turn on the appropriate genes.
The biggest implication of this breakthrough is in our understanding of diseases. When scientists compared the genome of a healthy person with that of a person with say Type 2 diabetes, there were some differences in an unused section of the chromosome that was located far from the gene under question. Now, they know that these unused sections are the switches that might be disrupting the gene's normal behavior.
There is still a lot more that needs to be understood before we can find a cure for diseases. How do these switches work? How many switches control a single gene? Can the switches be altered to treat a disease? It is an exciting time to be in medical research - if you love biology!

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Task 1. Read the article and choice True, False or No information.

1.  Many people thought that DNA was too simple to explain the vast diversity of life on our planet.
2. Genes influence how we look, act and even the diseases we may be prone to.
3. Chromosomes have tons of DNA which are part of the active genes.
4. Today DNA is used is understand and cure inherited diseases, create genetically-engineered medicines.
5. Scientists had identified 21,000 genes that make up our entire genetic sequence.
6. Scientists had understood 97% of DNA.
7. Scientists called unused DNA "Junk DNA".
8. DNA had only different amounts of the four bases (A,C,T,G).
9. Junk DNA are actually the main control centers that control how our genes work.
10. Groups of gene switches work together to turn on the appropriate genes.