3.8.1 DNA & gene mutations

• Mutation


  An alteration to the DNA base sequence - often arising spontaneously during DNA replication
• What are addition and deletion mutations?


  Where one or more nucleotides are either inserted or deleted from the DNA sequence - this will cause a frameshift
• What is a substitution mutation? 


  Where one nucleotide in the DNA sequence is replaced by another
• What is a duplication mutation? 


  Where one or more nucleotides duplicate and repeat
• What is an inversion mutation? 


  Where a group of nucleotides become separated from the DNA sequence, then rejoin in the reverse order
• What is a translocation mutation? 


  Where a group of nucleotides become separated from the DNA sequence, and are then inserted into the DNA of a different chromosome
• Why do mutations which cause a frameshift have a significant impact?

  Because the entire amino acid sequence produced will be different
• Mutagenic agent 


  Factors which increase the rate of gene mutation