Genetic mutations are heritable alterations in a cell's DNA, classified by the scale at which they act: small-scale mutations change individual nucleotides, while large-scale mutations rearrange segments at the chromosomal level. Small-scale mutations divide into point mutations, in which one base is substituted for another (as a transition between two purines or two pyrimidines, as a transversion across those classes, or through non-Watson–Crick mispairing), and frameshift mutations, in which an insertion or deletion of bases displaces the translational reading frame and thereby alters every downstream codon; large-scale mutations include translocation between nonhomologous chromosomes and inversion within a single chromosome. This topic belongs to molecular genetics and connects mutation mechanism to consequence — how a lesion in DNA propagates through transcription and translation to protein sequence, and how positional change can alter gene regulation independently of coding sequence.
Genetic mutations are heritable alterations in a cell's DNA, classified by the scale at which they act: small-scale mutations change individual nucleotides, while large-scale mutations rearrange segm…