The DNA double helix structure is a now a rather famous image.  The instructions for the cell are written in a code using only four letters, normally written as A, C, G, and T

The double helix - a code in four letters.

Most of us are familiar with the idea that computers work by reducing everything to a code of only two numbers '0' and '1'.

Binary is a code using only 1 & 0.

Also well known is the idea that Morse code can use dots and dashes to quickly transmit complex messages.  This code is frequently seen on war movies; the most famous Morse message being “...---...” or “SOS” the international distress signal.

Morse code uses two sounds 'dot' and 'dash' as the letters of the code.

So, it should be no surprise that something as complex as a human being can be reduced to a code of four letters.  However, the world is a rough place to live and our DNA code is constantly being damaged.

Our instruction manual can be damaged in several ways: The letters can be damaged, one of the strands can be damaged, or both of the strands can be broken at once. Sometimes two or more damage events happen near each other in a damage cluster.

What happens when this code is damaged?  Click here to find out what happens next.  Click 'damaged DNA' to find out how cells repair the damage.  .