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: -DNA is a dynamic and adaptable molecule. As such, the nucleotide sequences found within it are subject to change as the result of a phenomenon called mutation.

Detailed explanation-3: -Gene variants (also known as mutations) can have varying effects on health, depending on where they occur and whether they alter the function of essential proteins. Variant types include the following: Substitution. This type of variant replaces one DNA building block (nucleotide) with another.

Detailed explanation-4: -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.