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: -There are three types of DNA Mutations: base substitutions, deletions and insertions. Single base substitutions are called point mutations, recall the point mutation Glu—–> Val which causes sickle-cell disease. Point mutations are the most common type of mutation and there are two types.

Detailed explanation-3: -Mutations can be of many types, such as substitution, deletion, insertion, and translocation.

Detailed explanation-4: -Mutations in a gene can result in a change in the sequence of amino acids such as in frameshift mutations and in missense and nonsense mutations occurring in point mutations. However, point mutations can also lead to silent mutations.