During transcription, the original template strand is usually read from the 3' to the 5' end from beginning to end.

Later, a nucleotidyl tranferase is used to fill in the gap with the correct base, using the template strand as the reference.

Also important is L74, which interacts with the template strand to position it for base pairing with the nucleotide.

However, it is in the upstream direction (3' 5') for the copied template strand.

The semiconservative model seemed most reasonable since it would allow each daughter strand to remain associated with its template strand.

The polymerase complex suspends replication and is temporarily released from the template strand.

This results in some repeats found in the template strand being replicated twice into the daughter strand.

Subunits bump around until one of the right kind meets the copying machine in the right position to match the template strand.

DNA polymerase can add free nucleotides only to the 3' end of the template strand.

However, the cell must be able to differentiate between the template strand and the newly synthesized strand.