It is important that DNA polymerase accurately copies the template strand to avoid placing the wrong DNA nucleotide in the incorrect position. To avoid this, DNA polymerase ‘proofreads’ the complementary strand as it moves along the DNA. If it detects a mismatch, it can ‘snip out’ the wrong nucleotide and replace it with the right one. DNA polymerase has an accuracy rate of about 99%, which means that mistakes do occur every once in a while. A mistake results in a change to the DNA base sequence, which is known as a mutation. DNA mutations can have detrimental effects to the organism, since an altered base sequence can change the sequence of amino acids in a protein, causing it to fold differently and possibly lose its function.