BMB 401 Lecture Notes - Lecture 3: Photon, Non-Homologous End Joining, Pyrimidine Dimer
Document Summary
The dna polymerase needs a template for obvious reasons. It has to copy something so after the dna is unwound a single strand (ssdna) can then function as the template to be copied. It the(cid:374) (cid:272)atal(cid:455)zes the s(cid:455)(cid:374)thesis of a daughter stra(cid:374)d i(cid:374) a 5" (cid:1007)" dire(cid:272)tio(cid:374) (cid:271)e(cid:272)ause dna pol(cid:455)(cid:373)erase adds free (cid:374)u(cid:272)leotides to the (cid:1007)"-oh group. To get this ssdna the dna is unwound at the replication origin to form the replication bubble. The issue is dna polymerase cannot start synthesis of a new strand, it can only extend an exposed strand. To overcome this dna primase synthesizes short rna primers and these join to the exposed parent dna strands as they separate at the replication origin. This is then able to be extended by dna polymerase. The leading strand requires one primer whilst the lagging strand requires as many primers as there are okazaki fragments.