dna polymerase i has 5′ – 3′ polymerase activity, 5′ – 3′ exonuclease activity, and 3′ – 5′ exonuclease activity necessary for dna replication. mutations in the gene that encodes dna polymerase i may cause the enzyme to lose these activities. match the consequence of a loss‑of‑function mutation in dna polymerase i to the corresponding lost activity.