Mutations

• What are mutations?


  Random changes in genetic information
• How can mutations affect genetic material?


  They can alter genes or chromosomes
• What is the result of mutations on protein synthesis?


  They can result in no protein or an altered protein being synthesized
• What do single gene mutations involve?


  The alteration of a DNA nucleotide sequence
• What are the types of single gene mutations?


  Substitution, insertion, or deletion of nucleotides
• What are the types of single-nucleotide substitutions?


  Missense, nonsense, and splice-site mutations
• What is the effect of missense mutations?


  They result in one amino acid being changed for another
• What can be the consequences of missense mutations on proteins?


  They may result in a non-functional protein or have little effect
• What do nonsense mutations produce?


  A premature stop codon
• What is the result of nonsense mutations on protein length?


  They result in the production of a shorter protein
• What do splice site mutations affect?


  The bases at the point where an intron and exon meet
• What is the consequence of splice site mutations on mRNA?


  Some introns may be retained and/or some exons may not be included in the mature transcript
• What do insertions or deletions result in?


  Frame-shift mutations
• What is the effect of frame-shift mutations on protein synthesis?


  They cause all the codons and amino acids after the mutation to be changed
• What do chromosome mutations involve?


  The alteration of a DNA gene sequence
• What is a deletion mutation?


  A section of a chromosome is removed
• What is a duplication mutation?


  A section of a chromosome is added from its homologous partner
• What is an inversion mutation?


  A section of a chromosome is reversed
• What is a translocation mutation?


  A section of a chromosome is added to a chromosome that is not its homologous partner
• What can be the consequence of substantial changes in chromosome mutations?


  They often make them lethal
• What are the two main categories of mutations?


  • Single gene mutations
  • Chromosome mutations
• How do the effects of single gene mutations differ from chromosome mutations?


  • Single gene mutations can have varying effects on protein function
  • Chromosome mutations often lead to more severe consequences