Explain the term Mutations?

Mutations are changes in the genetic structure of an organism that occur at random or are the results of environmental causes. The majority of new mutations are harmful because of their randomness. In genetic cells, germ cell mutations can create lethal alleles, that cause death to the zygote. Lethal alleles can be either heterozygous dominant lethal traits or homozygous recessive lethal traits.

Somatic mutations take place in body cells. Both germ and somatic mutations can involve whole chromosomes or parts of chromosomes that have changed structure through inversions, deletions, and translocations, or by nondisjunction. Nondisjunction occurs when a replicated chromosome does not separate from its homolog during cell division, resulting in an extra chromosome in one cell and a deficiency in another.