DNA replication, the cell cycle and mitosis

Question 1

define semi-conservative replication

Answer 1

one original, one new; identical to parent strand

Question 2

DNA replication: stages

Answer 2

DNA helicase unzips (ATP used to break H-bonds);
RNA primer binds (synthesised by DNA primase); incoming dNTP anneal to template strand (origin of replication) by DNA polymerase; replicates in 5’ to 3’ direction, therefore “leading” and “lagging” strands created so asymmetric; RNA primers added along lagging strand are removed and replaced with DNA by repair DNA polymerase; ligase enymes anneal Okazaki fragments

Question 3

nucleoside analog drugs exploiting incoming dNTPs

Answer 3

lack 3’ OH so terminate as incoming dNTP cannot bind

Question 4

replication fork definition

Answer 4

Y-shaped junction that forms site where DNA is being replicated

Question 5

how does the replication fork move

Answer 5

a group of proteins work with DNA polymerase and primase; e.g. sliding clamp keeps polymerase on strand, single strand DNA binding protein prevent local folding

Question 6

DNA replication diagram

Answer 6

diagram from NAGE 2