Question

Can someone help explain

complete the following sentences on E coli DNA polymerase

1. In the DNA polymerase active site, a 3’ –O- nucleophile attacks a phosphate in the incoming dNTP to elongate the growing strand. Here, the reaction intermediate is stabilized by this metal ion:

2. The metal ion described in (a) is stabilized at the DNA polymerase active site by binding to side chains of which amino acid:

3. The 3-5’ exonuclease reaction is important for which process?

4. Which DNA polymerase(s) have 3-5’ exonuclease function?

5. The 5-3’ exonuclease reaction is important for which process?

6. Which DNA polymerase(s) have 5-3’ exonuclease function?

7. What is the function of DnaA?

8. What is the function of DnaB?

1. What is the function of DnaC?

j). What is the function of the β clamp?

Answer 1

a)Mg2+

c) it is important for proof reading

d) DNA pol 1, II ,III

e) it is mostly required for the elongation of the daughter DNA strand , as the DNA polymerase add dntp in 5' to 3' direction only .

f) only DNA poly 1 have 5'- 3' polymerase activity .

G) DnaA- it is the protein that activates the initiation of Dna replication .

H) function of Dna B-It act as a helicase upon binding of DnaB to the DNA of bacteria it leas to meting or opening up of the helical structure of the DNA so the dna repliication can happen easily.

I) DnaC - occurs as a primase , since dna replication in eukaryotes and prokaryotes need primer , so the major role of dnaC is to add 10 - 15 nt rna primer onto which DNA nucleotides are added .

j) function of BETA CLAMP :Holds the DNA polymerase in the place from where its copig or replicating the DNA so it does not dissociates from it .