A 0.9% solution of NaCl (saline) is isotonic to animal cells. When exposing animal tissues to solutions, it is common to use an isotonic solution such as Ringer's buffered saline so as to prevent osmotic effects and consequent damage to cells.
Mutations are permanent changes in the DNA due to changes in nucleotide sequences. Mutations that cause addition of extra nucleotides in a nucleotide sequences are known as frameshift mutations
