What is a mutation?

Some genes remain the same across all humans (and lots of different animal species too!); for example, most of us have two arms, two legs, two eyes, ten fingers & toes, a heart, a liver, etc.

However, there are parts of your genome that are unique to you and your family. These differences are what make you different from everyone else in the world; the shape of your nose, the freckles on your face, your height, hair colour, and much more!

These differences are called mutations, and most of the time they are completely harmless. At some point in the past, nucleotides in the DNA were added, removed, or swapped, thus changing the gene slightly.


If we relate the our genes back to sentences in a book, a mutation is like when there is a misspelling in a word. Sometimes, a change in spelling will not change the meaning of a word:

E.g.: Color –> Colour

In this case, the ‘u’ has been added, but one can still recognise the word as meaning the same thing – in fact, many people use “colour” all the time!

In other cases, a mutation can change the meaning of a gene completely:

E.g. Decrease –> Increase

Here, the “De” has been swapped for “In”, and the meaning of the word has now changed completely. If this mistake was part of an instruction manual, one would be doing the complete opposite of what they should. When these kinds of mistakes or mutations happen in the DNA of a cell, it can have a negative effect on how the cell functions.