<P> A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a sequence of DNA or RNA . Point mutations have a variety of effects on the downstream protein product--consequences that are moderately predictable based upon the specifics of the mutation . These consequences can range from benign (e.g. synonymous mutations) to catastrophic (e.g. frameshift mutations), with regard to protein production, composition, and function . </P> <P> Point mutation is a random SNP (single - nucleotide polymorphism) mutation in the deoxyribonucleic acid (DNA) that occurs at one point . Point mutations usually take place during DNA replication . DNA replication occurs when one double - stranded DNA molecule creates two single strands of DNA, each of which is a template for the creation of the complementary strand . A single point mutation can change the whole DNA sequence . Changing one purine or pyrimidine may change the amino acid that the nucleotides code for . </P> <P> Point mutations may arise from spontaneous mutations that occur during DNA replication . The rate of mutation may be increased by mutagens . Mutagens can be physical, such as radiation from UV rays, X-rays or extreme heat, or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA). Mutagens associated with cancers are often studied to learn about cancer and its prevention . </P>

Why is a frameshift mutation often much worse than a point mutation