How does DNA fit inside such a tiny cell?


Have you ever wondered what is the possible length of DNA that is present inside your cells? After all, its the DNA that contains information that is responsible for your physical traits – how you look, how you talk – your metabolic and physiological processes and essentially everything that defines you. The human genome contains approximately 3 billion base pairs of DNA packaged into 23 chromosomes. Thus, Each cell in our body contains around 2 meters of DNA. Moreover, it is estimated that the human body contains about 50 trillion cells—which works out to 100 trillion meters of DNA per human. Now, consider the fact that the Sun is 150 billion meters from Earth. This means that each of us has enough DNA to go from here to the Sun and back more than 300 times, or around Earth’s equator 2.5 million times!

However, our cells are extremely tiny. So, how does so much DNA possibly fit into a single cell? To achieve this, DNA strands have to be tightly wrapped and compacted into bundles.  This allows the cells to condense DNA into the microscopic space of the eukaryotic nucleus. The cells have evolved a mechanism of different levels of folding with the help of specialized molecules called Nucleosomes.

Learn more about Nucleosomes and DNA compaction in the video below:

The folding mechanism of DNA is believed to play a large role in how genes are read by the rest of the cell. Recent studies have also indicated that the information regarding how the DNA should fold is also coded into our DNA.

This implies that a second layer of information exists in the DNA (Inception?) i.e. the DNA sequence not only contains information to synthesize proteins and control gene expression, it contains information on its own folding. This could also mean that genetic mutations are not just caused by a change in the sequence of codes but also by a change in the way the DNA strands are folded.

Therapeutically, it is important because if we can devise a way to hide these unwanted mutations it could potentially be helpful in treating some genetic diseases.