* all definitions used are from McGraw-Hill Ryerson Biology 12 Textbook (Section 5.2)
APA citation: Braun, D., & Price, G. (2002). The Structure and Function of DNA. In Biology 12 (pp. 222-224). Whitby, Ont.: McGraw-Hill Ryerson.
Part 1: Initiation
- portion of the DNA double helix is unwound to expose the bases for new base pairing*
- creates a replication bubble*
1. Helicase unwinds the DNA by breaking hydrogen bonds between complimentary bases
2. Gyrase cuts the ends of the DNA to relieve the tension created from unwinding
3. SSBP (single stranded binding proteins) help to stabilize the newly unwound single strands of DNA as the unwound strands tend to re-form into a double helix
Lagging Strand:
4. Primase lands on one of the many origins of replication and synthesis an RNA primer for replication to start
5. Primer signals in Polymerase III
Part 2: Elongation
- two new strands of DNA are assembled using the parent DNA as a template*
- the new DNA molecules - each composed of one strand of parent DNA and one strand of daughter DNA (semi-conservative) - re-form into double helices*
6. Polymerase III pairs complimentary nitrogenous bases with the ones of the parent DNA
Lagging Strand:
7. Due to oxygen disassociation, polymerase will join the lagging strand once there is space to make use of time ----> short fragments of DNA = Okazaki fragments
8. Polymerase I removes the primer and fills in the space by extending the neighbouring DNA fragment*, it reviews and "cleans up" the work of Polymerase III
polymer: any large molecule that is made up of many smaller parts
-ase: enzyme, a protein that speeds up chemical reactions
DNA Polymerase: enzyme that helps put together small parts (nucleotides) of the DNA molecule
Part 3: Termination
- the replication process is complete and the two new DNA molecules separate from one another and the replication machine is dismantled*
9. Ligase glues the Okazaki fragments together in Lagging Strand
