Now the question is where exactly will these DNA primers actually bind to? Well, the sequence of the DNA primers are complementary to this flanking sequence and this flanking sequence here. And so what we see is one of the primers that has a complementary sequence to this one binds onto this end and the other one binds onto the opposite end of this complementary single strand of DNA. Now the reason this binds at the three end is because the DNA polymerase can only form the single strand of DNA. Colin can only elongate that DNA in the five to three direction. And so that primer must form at the five end.