And we'll see why that's important towards the end of this lecture. So let's move on to these four steps. So, in step one of the standard DNA sequencing, we have to actually obtain that DNA molecule that we want to sequence. So let's suppose we have a double stranded DNA molecule as shown on the board. Now, the second step of this process will involve DNA replication. And remember, DNA replication only takes place if the two strands of DNA have separated.