CELL201 Lecture Notes - Lecture 19: Geminin, Dna Replication, Okazaki Fragments
12 Apr 2018
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Document Summary
Cell cycle (ii: semi conservative dna replication. In eukaryotes, there are multiple initiation sites- replicons. At the centre of each replicon there is an ori. Every ori, in g1 there is a complex that is assembles orc and prc binds to ori. Helicase loaders cdc6 and cdt1 are recruited to the orc. Mcm proteins are then recruited to the origin. After replication begins, mcm proteins are removed from the origins and rebinding is prevented. Replication happens only once during the cell cycle: role of cdk in dna replication. Orc proteins and helicase loaders are phosphorylated and inactivated by cdk. Geminin is degraded in m phase: dna polymerases. Exonucleases- chew up dna from the ends, regardless of direction. Endonucleases- chews up dna in the middle, eg restriction enzymes. Dna polymerase has exonuclease activity, allows removal of incorrectly base-paired nucleotides. Rna primers at 5" e(cid:374)ds (cid:894)short stret(cid:272)hes of rna (cid:373)ole(cid:272)ules(cid:895) Dna poly(cid:373)erase does(cid:374)"t (cid:272)are if the starter is a rna or dna.
