Final answer:
A gene mutation is a permanent change in the sequence of bases in DNA. It can occur due to errors during DNA replication or exposure to mutagens in the environment. One type of mutation, called a point mutation, affects a single base and can occur when one base is substituted or replaced by another.
Step-by-step explanation:
A gene mutation is a permanent change in the sequence of bases in DNA. It can occur due to errors during DNA replication or exposure to mutagens in the environment. One type of mutation, called a point mutation, affects a single base and can occur when one base is substituted or replaced by another. Other types of mutations include insertions and deletions of one or more bases in the DNA sequence.