Why Does E

Multiple Choice

Why does E.coli need both DNA polymerase III and DNA polymerase I?

A) DNA polymerase III lacks the 5' → 3' exonuclease activity needed to remove RNA primers.
B) Each polymerase is specific for only one strand of DNA.DNA polymerase III acts only on the leading strand,and DNA polymerase I acts only on the lagging strand.
C) DNA polymerase I is needed to join the Okazaki fragments.
D) The DNA replication is bidirectional;one polymerase is used for each direction.
E) Only DNA polymerase I has proofreading ability.