Simply put, a genetic mutation comes from a change in the DNA; this change can result from an extrachromosomal element, an alteration of the inherited nucleotide...
The basic building block of nucleic acids, such as DNA and RNA. It is an organic compound made up of nitrogenous, a sugar, and a phosphate group (http://www.biology-online.org/dictionary/Nucleotide)
I believe it would be sperm
