Final answer:
In bacteria, DNA polymerase III (DNA pol III) is the enzyme primarily responsible for DNA synthesis during replication, while DNA pol I and DNA pol II are mainly involved in DNA repair.
Step-by-step explanation:
In bacteria, the enzyme responsible for most DNA synthesis is DNA polymerase III (DNA pol III). This enzyme is essential for the addition of deoxyribonucleotides to the growing DNA chain during replication. DNA pol III possesses high processivity and functions to elongate the nascent DNA strand. DNA pol I and DNA pol II, on the other hand, are primarily involved in repair functions, though DNA pol I also plays a role in removing RNA primers and filling in the gaps with DNA.
The replication process is initiated at origins of replication, where proteins recognize specific nucleotide sequences to begin unwinding the DNA helix, preparing it for the action of various enzymes, including DNA polymerases. Energy for the nucleotide addition is supplied by the hydrolysis of triphosphate nucleotides, which releases energy to form phosphodiester bonds.