In chemistry and atomic physics, the main group is the group of elements whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements
This is the definition of a DNA mutation.
Depending on which part of the genome is affected, the consequences of a mutation may vary. A mutation is said to be hereditary if the mutated genetic sequence is transmitted to the next generation (see germinal mutations). It is one of the elements of biodiversity and one of the many factors that may be involved in the evolution of the species.
