Variation or mutation Any change to the sequence of bases(genotype) in the dna of an organism is a mutation or variation (e 变或变异) The change may be a single- base change called a point mutation or involve a much larger sequence of dna in which case it is called a multi-site mutation. DNA may be deleted, inserted, inverted, duplicated or substituted. (that means the change of structure or amount).Any change to the sequence of bases (genotype) in the DNA of an organism is a mutation or variation(突 变或变异). The change may be a single-base change called a point mutation or involve a much larger sequence of DNA in which case it is called a multi-site mutation. DNA may be deleted, inserted, inverted, duplicated or substituted .(that means the change of structure or amount). Variation or mutation