BIO 201 Lecture Notes - Lecture 33: Semiconservative Replication, Dna Replication, Chromosome
6 Sep 2018
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The challenges of replication and how we* overcame them. *we = common ancestor to all extant species, as far as we know. Parent strand serves as a template for synthesis of new dna. New strand is always the reverse complement of template strand. Additio(cid:374) of (cid:374)u(cid:272)leotides o(cid:374)l(cid:455) o(cid:374)to 3" e(cid:374)d (cid:894)5" to 3" pol(cid:455)(cid:373)erizatio(cid:374)(cid:895). Template is read fro(cid:373) the 3" e(cid:374)d towards the 5" e(cid:374)d. Replication bubble: where the strands of dna have come apart for replication. Replication bubble increases in size as replication proceeds. Replication forks: where dna is being actively polymerized. In bacteria, replication always begins at a sequence called the origin of replication (ori) In bacteria, there is usually one origin per chromosome. ~ 40 minutes to replicate ~5mbp (~2000 bases per second!) Replication of human chr. 1 (250 mbp) would take > 30 hrs if only one origin. Dna replication tightly regulated (g1/s checkpoint control)
