We take a sample. It might be blood or saliva… essentially all these samples have cells, and you probably know about cells from what you’ve learnt at school – there’s lots of other stuff in there. We then break the cells open and using chemicals, we get rid of all the other stuff. Then we’re just left with the DNA, which you can see in a test tube as a fluffy white-ish blob. So, that’s DNA!
Bu then we’re interested in looking at the actual sequence of the DNA… that takes a whole load more experimental techniques (which are fairly straight forward), to get the strings of ACGT’s that tell us what the DNA sequence is!