Replication Lagging Strand LAGGING STRAND Semiconservative synthesis of the leading strand in a linear chromosome can proceeds normally to the end of the double helix. On the lagging strand, after the last RNA primer is removed, there is no free 3'-OH for DNA polymerase to elongate. The gap on the lagging strand leads to shortening of the chromosome after each round of synthesis. This chromosome shortening may play a role ag ing of somatic cells, and must be avoided in germ cells .