Final answer:
The base complementary rule is used to join free nucleotides to the exposed bases of DNA. Only certain types of base pairing are allowed, such as A with T and G with C. If an incorrect base is added, it is removed and a correct nucleotide is added again.
Step-by-step explanation:
In DNA, nucleotides are joined to exposed bases using the base complementary rule. This means that only certain types of base pairing are allowed, such as A with T and G with C. The DNA strands are complementary to each other, so if one strand has the sequence AATTGGCC, the complementary strand would have the sequence TTAACCGG.
During DNA replication, if a newly added base has paired correctly with the base in the template strand, the next nucleotide is added. If an incorrect base has been added, the enzyme DNA pol III makes a cut at the phosphodiester bond and removes the wrong nucleotide. The correct nucleotide is then added again.