What is the Software for Life?

 By Ajay Dasgupta; Illustration by Shinod AP

We all use computers. If you use Windows on your machine, like me, you will have a small button at the the bottom of your screen called 'Start'. Every machine in the world which has the Windows software installed has to have that button. However, we can have different screen colours, different text sizes, wallpapers etc.

Similarly our bodies are essentially the same, but we have different colours, sizes, shapes and structures. Our body also has a software which is responsible for these differences between one human being and another. It is called the DNA.

Where and what is the software?
We all know that every living organism is made up of small units called cells. These cells are the building block of a organism. The human body is nothing but a collection of millions of such cells. Each cell performs a specific task in our body, the blood cells carry oxygen and food while the cells of our skin protect and give us colour.

But how does a cell know what it has to do? Imagine what would happen if the skin cells performed the functions of our blood cells.

The nucleus and the genetic code
Every cell has a tiny compartment inside it, this is called the nucleus. All the information about the cell's job is written on a molecule called the DNA and stored inside the nucleus. We could say the nucleus is like the hard-disk of your computer. This information is called the genetic code.

DNA or deoxyribonucleic (spelled de-oxy-ribo-nucleic) acid, is the master molecule of life on earth. It is shaped liked a twisted ladder called a double helix. The ladder has rungs made up of four different molecular parts. These rungs, called the nucleotides, spell out the hereditary instructions for making a given organism.

Every life form on earth has a different set of instructions. That is why one animal is different from another and why you are taller than your father.

When an organism reproduces, it passes on its DNA to its offspring. When you were born, you got half of your DNA from your father and the other half from your mother. This is the reason why some of your features are like those of your mother while others like your father.

Every creature on earth, be it a plant or an animal carries the DNA in it. The DNA is the wonder molecule which propagates life on earth.