In IB Biology HL D1.1.9, DNA polymerase III removes mismatched nucleotides from the 3′ end of a growing strand. This proofreading improves copying accuracy and reduces mutations.
Living organisms have mechanisms for preventing or reducing change.
Explain how mutation is avoided during DNA replication.
a. complementary base pairing (between DNA nucleotides);
b. adenine pairs with thymine and cytosine pairs with guanine;
c. new strands with same/correct sequence/copy produced by semiconservative replication OR
semiconservative replication is using a template strand (to make a new strand);
d. DNA polymerase (III) adds nucleotides to the growing chain/to the template strand;
e. proofreading is correction of errors/mutations (during DNA replication)
f. proofreading by DNA polymerase III
OR
error in replication/nucleotide with mismatched base detected by DNA polymerase III
g. DNA polymerase III has 3′ to 5′ exonuclease activity
OR
DNA polymerase III reverses and excises nucleotide
OR
(mismatched) nucleotide removed and replaced (by DNA polymerase III);