Lungs, bronchi, bronchus, diaphragm, trachea, alveoli, pharynx, nasal cavity, etc.
I guess it is <span>DNA Polymerase enzyme</span>
Mutation can be both beneficial and harmful.
A very common beneficial mutation is camouflage and natural selection. The organism will acquire the change and pass it on to their offspring.
A harmful mutation can be diseases or a common harmful mutation, Down syndrome. Which gives a person an extra chromosome.
