22 - DNA polymerase mcqs

question : DNA polymerases have

a- 3' - 5' polymerase activity
b- 5' - 3' polymerase activity
c- 3' - 5' exonuclease activity
d- 5' - 3' exonuclease activity
e- endonuclease activity

answer : b , c , d are the answers .

DNA Polymerase 1 has both proof reading and excision repair activity , that is it has both 3' - 5' exonuclease activity and 5' - 3' exonuclease activity respectively. where as the DNA polymerase 2 and 3 have only proof reading activity and no excision repair activity, that is they have 3' - 5' exonuclease activity and no 5' - 3' exonuclease activity.

all the three DNA polymerases have only 5' -3' polymerase activity only.