Genome editing is a way to change a DNA code. It uses specialised “molecular scissors” called nucleases to cut the DNA chain at a specific site. One of the methods of doing this is known as CRISPR-Cas9, but there are others. We can guide these “molecular scissors” to cut at a specific part of the DNA using a short molecule called RNA that we can design in the lab. RNA is very similar to DNA, but it has only one strand. An RNA molecule can find and stick to a piece of DNA if they share the same sequence of chemical letters.

Now that we have read the whole human genome and know all of its DNA letters, we can choose exactly where to cut. After cutting the DNA, we can decide what happens to it: we can mend it with another piece of DNA so that we can correct mutations (mistakes in the DNA code which can cause disease) or put in a new piece of DNA; or we can deliberately break the DNA strand to see what happens if that particular part of the DNA instruction manual is broken or missing.

If you are interested in finding out more about genome editing, then please do have a look at the series of videos that the Biochemical Society produced on this topic, in collaboration with the Federation of European Biochemical Societies (FEBS), one of which also covers our “Scientific Scissors” activity.