Which component must act first for DNA Polymerase III to function?

For DNA Polymerase III to initiate the synthesis of a new DNA strand, it requires a short primer that provides a free 3' hydroxyl (OH) group to which nucleotides can be added. This primer is synthesized by an enzyme called primase. Primase adds RNA nucleotides to form a primer that is complementary to the DNA template strand, ensuring that DNA Polymerase III has the necessary starting point for DNA replication to proceed.

Once the primer is in place, DNA Polymerase III can begin adding DNA nucleotides, which is critical for the replication process. Without this primer provided by primase, DNA Polymerase III would not have the initial 3' end it needs, rendering it unable to act on its own.