1. Sudden and heritable mutation in genomic DNA molecules (genemutation). From a molecular level, gene mutation refers to a change in the base pair composition or sequence of a gene's structure. Although genes are very stable and can accurately replicate themselves when cells divide, this stability is relative. Under certain conditions, genes can suddenly change from their original form of existence to another new form of existence. That is, a new gene suddenly appears at a site, replacing the original gene. This gene is called a mutant gene. As a result, new traits that the ancestors never had suddenly appeared in their offspring's performance.

2. A structural change within a gene that can be inherited. Also called point mutations, they usually cause certain phenotypic changes. Mutation in a broad sense includes chromosomal aberrations. Mutation in the narrow sense refers specifically to point mutations. In fact, the boundary between distortion and point mutation is not clear, especially for subtle distortion. Wild-type genes become mutant genes through mutation. The term mutant refers to both the mutated gene and the individuals with this mutated gene.

3. Gene mutations can occur at any stage of development, usually during the DNA replication period, that is, the interphase of cell division, including mitotic interphase and meiotic interphase; at the same time, gene mutations and DNA Replication, DNA damage repair, carcinogenesis and aging are all related. Gene mutation is also one of the important factors in biological evolution, so studying gene mutation has broad biological significance in addition to its own theoretical significance. Gene mutation provides mutant types for genetic research and materials for breeding work, so it also has practical significance in scientific research and production.