Mutations

• What are single gene mutations?


  They involve the alteration of a DNA nucleotide sequence as a result of substitution, insertion or deletion.
• What are mutations?


  The changes in the DNA that can result in no protein or an altered protein being synthesised
• What is substitution?


  The replacement of one base
• What is insertion?


  The addition of one base
• What is deletion?


  The removal of one base
• What are the 3 effects of substitution?


  1. Missense - one amino is changed for another
  2. Nonsense - premature stop codon
  3. Splice-site - introns may be retains or exons removed
• What are the effects of insertion/deletion?


  Insertion/deletion results in frame-shift mutations. This causes all of the codons and all of the amino acids after the mutation to be changed. This a major effect on protein structure.
• What is a chromosome mutation?


  They alter the structure or number of chromosomes. Due to the substrate changes caused by a chromosome they are often lethal.
• What is a duplication chromosome mutation? And what conditions can be associated with this?


  A section of a chromosome is added from its homologous pair. This can result A section of a chromosome is added from its homologous pair. This can result in a set of genes being repeated. Associated conditions include:

  • cancer
  • charcot-marie tooth disease
• What is a deletion chromosome mutation? And what conditions can be associated with this? 


  Where a section of chromosome is removed. This results in part of the chromosome being lost. Associated conditions are:

  • cystic fibrosis
  • turner syndrome
  • cri-du-chat syndrome
• What is an inversion chromosome mutation? And what conditions are associated with this?

  A section of the chromosome is reversed. DNA may or may not be lost in the process. Associated conditions:

  • Haemophilia A
• What is a translocation chromosome mutation? 


  A section of a chromosome is added to a different chromosome, not its homologous pair.
• Way to remember mutations - Tea Is Definitely Drinkable

  T - Translocation

  I - Inversion

  D - Deletion

  D - Duplication