A frameshift mutation can be described as a genetic mutation in which a single nucleotide or more than one nucleotide is inserted or deleted from the sequence of the DNA. As the gene expresses itself in the form of triplets of a genetic code, insertion or deletion can cause devastating changes in the genetic code due to which wrong proteins will be synthesized.
Frameshift mutations can be more noticeable than the substitution mutation. In a substitution mutation, only one of the nucleotides is shifted with another. The entire genetic code is not affected by it.
Mitochondrial DNA mutation occurs at a constant rate throughout history. Thus, each different base in Mitochondrial DNA is able to show just how long ago the 2 species diverged from each other. Hope this helps! :)
