5'--------->3'

5' PO₄ -------- A T T C C CG T A T C T G-----------OH 3'

3' OH -------- T A A G G GC A T A G A C----------PO₄ 5'

3'<---------5'

Note the strands are oriented in opposite directions. The PO₄ of the upper strand lies opposite the OH of the lower strand.