AP BIOLOGY

Detailed explanation-1: -A gene variant is a permanent change in the DNA sequence that makes up a gene. This type of genetic change used to be known as a gene mutation, but because changes in DNA do not always cause disease, it is thought that gene variant is a more accurate term.

Detailed explanation-2: -Mutations can be of many types, such as substitution, deletion, insertion, and translocation.

Detailed explanation-3: -While mutations always change the DNA sequence, they do not always cause a change in the resulting protein or an obvious effect on the organism. This can occur because most amino acids can be coded by two or more different codons.

Detailed explanation-4: -The DNA in any cell can be altered through environmental exposure to certain chemicals, ultraviolet radiation, other genetic insults, or even errors that occur during the process of replication.