mutations

Cards (15)

  • a mutation is a random spontaneous change in an organisms genome.
  • There are 2 types of mutations:
    • gene mutations: change in the DNA structure a gene
    • chromosome mutations: change in the structure or number of chromosomes
  • Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of:
    • the substitution of nucleotides. (replacing 1 nucleotide with another).
    • insertion of nucleotides.
    • deletion of nucleotides.
    1. Missense mutations – result in one amino acid being changed for another. This may result in a non-functional protein or may have little effect on the protein depending on the amino acid that has been changed.Example Sickle cell disease.
    1. Nonsense mutations result in premature stop codon being produced which results in a shorter protein.Example Duchenne Muscular dystrophy.
    1. Splice site mutations result in some introns being retained and/or some exons not being included in the mature transcript.Example beta thalassemia.
  • The effect of an insertion or deletion of a nucleotide results in frame shift mutations. ,
    • Cystic fibrosis – Deletion
    • Tay-Sachs disease - Insertion
  • Frame shift mutations cause all of the codons and all of the amino acids after the mutation to be changed.
    This has a major effect on the structure of the protein produced.
  • CHROMOSOME MUTATION 1:
    Duplication – a section of a chromosome is added from its homologous partner.
  • CHROMOSOME MUTATION 2:
    Deletion is where a section of the chromosome is removed.
  • CHROMOSOME MUTATION 3:
    Inversion is where a section chromosome is reversed.
  • CHROMOSOME MUTATION 4:
    Translocation is where a section of a chromosome is added to a chromosome,
    that is not its homologous partner.
  • The substantial changes in chromosome mutations often make them lethal.
  • Changing one amino acid could cause a protein to function less effectively because the structure of the protein is altered, or the protein does not fold properly.