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A mutation is an alteration in the genetic material of a cell that is transmitted to the cell's offspring. may be spontaneous (the result of accidents in the replication of genetic material) or induced by external factors (e.g., electromagnetic radiation and cert ....

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.... in units called codons, each of which specifies a particular amino acid. (Proteins are composed of amino acids.) A codon consists of a sequence of three bases--for example, GAG or TCA. The four bases can be assembled into 64 possible codons. Because proteins are built from only 20 amino acids, most amino acids are specified by more than one codon. occur when one base is substituted for another or when one or more bases are inserted or deleted from a gene. Substitution affect only one codon, and in most cases the effect is minimal. One reason is the redundancy of the genetic code mentioned above. Because many codons mean the same thing, the altered ....