E. coli was the subject of the study OriC is the start of replication Terminus is the end of replication
An enzyme that syntheses nucleic acid
A short stretch of DNA or RNA nucleotides hydrogen-bonded to its complementary strand Starts the DNA replication process The known primer is called the DNA Primase
DNA Polymerase I ▪ 1 st identified polymerase ▪ Removes repeated DNA primers that are necessary for DNA replication DNA Polymerase II ▪ Responsible for DNA repair DNA Polymerase III ▪ Large multi subunit enzymes ▪ Made up of seven proteins ▪ Add successive new nucleotides into the template
Ability to synthesize polynucleotide strands All requires a primer, a short stretch of DNA or RNA nucleotides hydrogen-bonded to its complementary strand Synthesize in 5’ to 3’ direction by copying the 3’ to 5’ in the template Adds new nucleotides to the 3’ OH of a primer
They can also be “Nucleases” (ability to remove nucleotide) Endonucleases (cuts DNA internally) Exonucleases (chew away at an end of DNA) Has a 3’ to 5’ exonuclease activity called PROOFREADING FUNCTION
Unzips the DNA molecule in preparation for replication
REPLICATION REPLICATION
Leading Strand The strand that receives the continues strand (3’ to 5’ direction) Lagging Strand The strand of the template DNA double helix that runs from 5’ to 3’. The mode of replication is in discontinuous fashion.
Short stretches of a newly synthesized DNA on a lagging strands Discovered by Reiji and Tsuneko Okazaki
DNA Primase Made up of RNA primer complementary to a DNA template DNA Helicase An enzyme that opens up the helix of the DNA DNA Gyrase An enzyme that can remove the torsional strain introduced by opening the helix
Single-strand binding protein (ssb) Covers the unwound DNA DNA pol I Removes primers with its 3’ to 5’ exonuclease activity and then replaces this with DNA DNA Ligase Creates a phosphodiester bond between adjacent to the Okazaki fragments
Initiation (Bubble) Elongation Termination
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