PHYS 1010 Lecture Notes - Lecture 1: Pyrimidine, Nitrogenous Base, Purine

• School: York University
• Department: Physics and Astronomy
• Course: PHYS 1010
• Professor: Christopher Bergevin

Document Summary

4. 3: dna replication and repair: when the structure of dna was discovered by watson and crick, the structure of dna immediately suggested how dna was able to replicate. Separating the dna strands: eukaryotic replication is similar to prokaryotic replication, just more complex, replication begins when proteins bind to specific sites on dna known as the replication origin. In eukaryotic dna, it has multiple origins of replication where in prokaryotes, usually has one of these sites. The enzyme, helicase separates the two strands of the double helix to expose the nitrogenous bases. Gyrase/topoisomerase relieves the tension caused by the unwinding of the dna molecule. Single- stranded binding proteins (ssbs) attach to the template strands, preventing the complementary bases from bonding together again (complementary bases have a tendency to attach together). The open structure after the h-bonds are broken is referred to as the replication fork, an assymetrical, 2 single strands that run in anti-parallel directions.