3 5 DNA replication in 3 Okazakifragment 1kb 5 (semi-discontinuous replication ! 5 At least one strand of DNA replication in Okazakifragment Ikb
At least one strand of DNA replication in Okazaki fragment 1kb 5‘ 3‘ 5‘ 3‘ DNA replication in Okazaki fragment 1kb 5‘ 3‘ 5‘ 3‘ （semi-discontinuous replication ! ） ？
T4 ligase mutant 6-Short DNA pieces 5 60 sec 40se0 20 sec 10 sec 1 2 3 Relative distance from top of tube
T4 ligase mutant
b)Second proof of semi-discontinuous replication dump fragment in DNA
b)Second proof of semi-discontinuous replication dump fragment in DNA
dUTP dTTP=1:300 in cell DNA中不能有U? 少数dUTP dUTPase一 dut gene 突变频率= 1/1200!? -A- -J- Ungase 尿嘧啶N-糖基酶 U ung
dUTP : dTTP = 1 ：300 in cell -A- -T- -G - -C- A U G U dUTPase dut gene 少数dUTP DNA 中不能有U ? -A- -T- 突变频率 = 1/1200 ！？ -A- -A- -U- - - Ungase ung 尿嘧啶-N-糖基酶 U
denature dump fragment 1200base Okazaki fragment ●ung-→ dump fragment longer ●dut-→ dump fragment shorter
U U denature dump fragment ~ 1200base ~ Okazaki fragment ● ung – dump fragment longer ● dut – dump fragment shorter A A