Final answer:
DNA Pol I has a 5'→3' exonuclease activity which is removed by mild protease treatment, leaving the Klenow fragment with polymerization and proofreading activities. This allows full-length DNA Pol I to be used in nick translation, an important technique in DNA research.
Step-by-step explanation:
DNA polymerase I (pol I), exists as a monomeric enzyme and possesses several activities related to DNA replication and repair. By treating DNA Pol I with a mild protease, a specific structural domain can be removed, which has 5'→3' exonuclease activity used for the removal of RNA primers. The remaining portion, known as the Klenow fragment, possesses both polymerization and proof-reading activities but lacks the 5'→3' exonuclease activity. This enzymatic makeup allows the full-length DNA Pol I to be utilized for nick translation in vitro, a process vital in DNA research and molecular cloning techniques.
Okazaki fragments, short stretches of DNA synthesized on the lagging strand, require DNA polymerase I for the removal of the RNA primer nucleotides, and the eventual replacement with DNA nucleotides. DNA ligase then joins these Okazaki fragments together to complete the DNA strand.