Mutations are random changes to the base pair sequence that occur in a gene or chromosome. Most mutations have no effect on the phenotype (the observable characteristics of an organism) If a base pair changes, it could code for a different amino acid which would lead to a different protein being made. This can affect the function of the protein. When mutations lead to the development of a new phenotype, most have a small effect on the organism . Occasionally the new phenotype will give the individual a survival advantage over other members of the species. Some mutations can lead to harmful changes. Mutations happen spontaneously but the incidence of mutations can be increased by exposure to: ionising radiation (gamma rays, -rays and ultraviolet rays chemical mutagens (for example, chemicals in tobacco) 6. Explain how a mutation in this sequence could result in a change in the protein.