Final answer:
High fidelity in DNA replication refers to the precise duplication of the DNA sequence, maintained through proofreading and repair mechanisms such as DNA pol I and III to correct mistakes and prevent mutations. DNA ligase also contributes to this high fidelity by assisting in fixing any remaining errors after proofreading.
Step-by-step explanation:
High Fidelity in DNA Replication
“High fidelity” due to proofreading during DNA replication refers to the accurate copying of the DNA sequence, ensuring that any mistakes are corrected. This is a critical function because errors in replication could lead to genetic mutations which can have serious consequences, such as diseases like cancer. During this process, DNA polymerases play an essential role in checking the newly-added nucleotides against the template strand. If an incorrect base is detected, these polymerases, particularly DNA polymerase I and III, have a 3' exonuclease activity that removes the incorrect nucleotide. This action allows a correct base to be inserted, thereby maintaining the integrity of the genetic code.
The presence of DNA ligase and other repair mechanisms ensures that the DNA is correctly pieced together after proofreading, further minimizing the occurrence of mutations. All these repair processes contribute to the impressive accuracy of DNA replication in cells.