Steps involved in DNA replication Steps involved in DNA replication. This figure describes DNA replication in an E coli cell, but the general steps are similar in eukaryotes. A specific interaction of a protein (the dnaA protein) to the origin of replication (oriC) results in local unwinding of DNA at an adjacent A+T-rich region. The DNA in this area is maintained in the single-strand conformation (ssDNA) by single-strand-binding proteins (SSBs). This allows a variety of proteins, including helicase, primase, and DNA polymerase, to bind and to initiate DNA synthesis. The replication fork proceeds as DNA synthesis occurs continuously (long red arrow) on the leading strand and discontinuously (short black arrows) on the lagging strand. The nascent DNA is always synthesized in the 5′ to 3′ direction, as DNA polymerases can add a nucleotide only to the 3′ end of a DNA strand. Source: DNA Organization, Replication, & Repair, Harper's Illustrated Biochemistry, 30e Citation: Rodwell VW, Bender DA, Botham KM, Kennelly PJ, Weil P. Harper's Illustrated Biochemistry, 30e; 2015 Available at: https://accesspharmacy.mhmedical.com/DownloadImage.aspx?image=/data/books/1366/rod_ch35_f013.png&sec=73245095&BookID=1366&ChapterSecID=73245009&imagename= Accessed: October 13, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved