Lesson Objectives: Explain the process of DNA replication and the role of the major proteins involved. Step 1: Helicase Step 2: Single-Stranded Binding Proteins Helicase unzips the double helix by breaking the hydrogen bonds between the nitrogenous bases. • To make sure that the separated DNA strands stay apart, single-stranded binding proteins bind to each strand of DNA. • Alia Kanan, 2019 Step 3: Primase • DNA Polymerase adds/synthesizes free-floating nucleotides to form hydrogen bonds with the template strand Step 4: Primase DNA Polymerase • • DNA Polymerase adds/synthesizes free-floating nucleotides to form hydrogen bonds with the template strand in the 5’ to 3’ direction of the new strand. DNA polymerase enzymes bond the nuclotides together to form the double helix. Step 5: Ligase • Nucleotides are added in the 5’ to 3’ direction of the NEW strand. • The leading stand is continuous while the lagging strand is discontinuous and produces small Okazaki fragments. • Ligase “glues” the fragments together. DNA Replication Step-by-Step Proof-reading • DNA polymerase can find and correct errors as replication is proceeding.