BSC-2010 Lecture Notes - Lecture 3: Dna Polymerase I, Okazaki Fragments, Dna Ligase
Document Summary
You (cid:272)a(cid:374) o(cid:374)l(cid:455) (cid:271)uild o(cid:374) a 3(cid:859) stra(cid:374)d o(cid:374) dna. (cid:455)(cid:374)thesis of leadi(cid:374)g stra(cid:374)ds is (cid:272)o(cid:374)ti(cid:374)uous i(cid:374) 5(cid:859) to 3(cid:859) e(cid:374)d. The lagging strand elongates the other strand. Dna polymerase must work in the direction away from the replication fork. The lagging strand is synthesized by dna polymerase iii as a series of segments called okazaki fragments. The leading strand is synthesized towards the replication fork; the lagging strand is synthesized away from the replication fork. Dna polymerase i can remove rna nucleotides and fill in the gap with dna nucleotides. Fills in the gaps with dna nucleotides. Ends of okazaki fragments must be joined together. Dna ligase can join the 5(cid:859) e(cid:374)d of o(cid:374)e dna (cid:373)ole(cid:272)ule (cid:449)ith the 3(cid:859) e(cid:374)d of a(cid:374)other. Eukaryote cells do not have termination sequences. Every time you copy a chromosome, telomeres get shorter. Eukaryotic chromosomal dna molecules have repetitive, non-coding nucleotide sequences at their ends called telomeres.