Final answer:
The DNA polymerase I Klenow fragment lacks the 5'→3' exonuclease activity, which is responsible for removing RNA primers during DNA replicaation. The Klenow fragment retains polymerization and proofreading activities, necessary for DNA synthesis and correction of errors.
Step-by-step explanation:
The DNA polymerase I Klenow fragment is missing the 5'→3' exonuclease activity. This exonuclease activity is responsible for removing RNA primers at the terminal end of DNA strands, particularly during the replication of the lagging strand, in a process that involves the synthesis of Okazaki fragments. DNA polymerase I, in its complete form, not only possesses the ability to synthesize new DNA strands by incorporating deoxynucleotides but also has a crucial role in the process of DNA repair and removal of RNA primers through its 5'→3' exonuclease activity.
Once the Klenow fragment is produced by mild protease treatment which removes the specific domain with 5'→3' exonuclease activity, the remaining fragment retains only the polymerization and proofreading activities. These are essential for the DNA synthesis steps where the polymerase adds nucleotides one by one, and for the correction of any misincorporated bases, therefore maintaining high accuracy and fidelity of DNA replication.