The ability of DNA polymerase to digest a DNA strand from one end is called its exonuclease activity. Exonuclease activity is used to digest RNA primers and also to proofread a newly made DNA strand. DNA polymerase I does not change direction while it is removing an RNA primer and synthesizing new DNA. It does change direction during proofreading.
A. In which direction, 5' to 3' or 3' to 5', is the exonuclease activity occurring during the removal of RNA primers and during the proofreading and removal of mistakes following DNA replication?
B. Figure 11.17 shows a drawing of the 3' exonuclease site. Do you think this site would be used by DNA polymerase I to remove RNA primers? Why or why not?