BIOL 205 Lecture Notes - Lecture 4: Dna Gyrase, Helicase, Dna Clamp
Document Summary
Dna synthesis is fast and accurate: 2000 nucleotides/second- in e. coli two forks moving at 1000 nucleotides/second, e. coli genome 5 million base pairs- 40 minutes, 1 nucleotide error in 1010inserted (thanks to. Initiation of replication: the origin of replication in e. coli is termed oric. Origin of chromosomal replication: three types of dna sequences in oric are functionally significant. Gatc methylation sites: many proteins are required. Unwinding the double helix: two enzymes open helix and prevent overwinding. Helicase- clamps to dna breaks hydrogen bonds ahead of dna synthesis. Ssb single strand dna binding proteins bind to unwound dna and prevent it from re-forming: dna replication is initiated by the binding of. This binding stimulates the cooperative binding of an additional 20 to 40 dnaa proteins to form a large complex. Travels along the dna in the 5" to 3" direction. Dna replication complexes: dna helicase and primase are physically bound to each other to form a complex called the primosome.
