If you use only a forward primer, DNA amplification cannot occur as only the template strand will be synthesized but it will not have a complementary strand to bind to. Two primers – a forward primer and a reverse primer – are essential for amplifying any DNA sequence. Each primer is responsible for facilitating specific actions that help with DNA amplification. The forward primer uses the bottom strand as a template to synthesize the upper strand. The reverse strand uses the upper strand as a template and synthesizes the lower strand.