2 Semidiscontinuous Replication (a)Continuous: 5 Re plication fork 5 3 3 3 3 5 51 53 3 (b)Semidiscontinuous: 5 lagging strand 5 Replication fork 3 Leading strand 3 53 (c)Discontinuous: 3 3 3 3 5 3
Leading strand lagging strand Replication fork Replication fork 2 Semidiscontinuous Replication
OK! 3 5 5 3 59 36 How
3‘ 5‘ OK ! How ? 5‘ 3‘ 5‘ 3‘
a)first proof of semi-discontinuous replication Okazaki fragment 1968 Reiji Okazaki E.coli 2”,7,15”,60” 20℃indT-H330” pulse-labelingin dT-H3 pulse-chase stop in0℃ transfer to dT then continue D.S.DNA ↓ S.S.DNA ↓ Density gradient of sucrose ↓ Measure H3-T
a) first proof of semi-discontinuous replication Okazaki fragment 1968 Reiji Okazaki E.coli 2’’, 7’’, 15’’, 60’’ pulse-labeling in dT-H3 stop in 0℃ D.S. DNA S.S. DNA Density gradient of sucrose Measure H3 -T pulse-chase 20℃ in dT-H3 30’’ transfer to dT then continue
Pulse labeling experiments SH-T pulse long
3H-T pulse 3H-T long Pulse labeling experiments
HP-T b品品PNA ↓120sec (I'wd) 30s0 15 sec 7s00 (Prok.400Nt/sec) 1 3 Relative distance from top of tube DNA replication in Okazaki fragment 1kb
H3 -T pulse-labeling pulse-chase 120’’ 60’’ 7’’ 15’’ 2’’ 10S (1kb) 40S (Prok. 400Nt/sec) DNA replication in Okazaki fragment 1kb