Mississippi State Biology 1 Practice Test

During DNA replication, the leading strand is synthesized continuously in the same direction as the replication fork is opening. It requires only one primer to initiate the synthesis of the new DNA strand. This primer is a short segment of RNA that provides a starting point for DNA polymerase to begin adding DNA nucleotides. Once this primer is in place, the DNA polymerase can continuously add nucleotides in a 5' to 3' direction, effectively elongating the leading strand with no need for additional primers along its length.

This is in contrast to the lagging strand, which is synthesized in short segments, requiring multiple primers for each segment (Okazaki fragments). Understanding the role of primers in leading versus lagging strand synthesis highlights the efficiency of continuous synthesis for the leading strand as opposed to the disjointed method necessary for the lagging strand.