I'm using a protocol in which I digest a antibiotic resistance gene with KpnI and BamHI and it leaves overhangs on the same strand 3'-5'. Then I make two fragments A e B as showed in the picture with overhangs as well. After I make a PCR and joins the three together but I don't understand how they complement each other, because it seems the overhang in fragment A is on strand 3'-5'. And fragment B has the overhang on 5'-3'. Please help. Thank you.