mutations

• • population - group of organisms living together in a particular place at a particular time
  • gene pool - sum of all alleles in a given population
• Mutations:

  (permanent change in a gene/chromosome that could potentially lead to a new characteristic in an organism)

  • occurs when a new allele is formed resulting in a different variation of the trait
  • mutant - organism with a characteristic resulting from a mutation
  • chromosomal mutation - all or part of chromosome affected
  • induced mutations - mutagens within the environment
  • spontaneous mutations - random error in biological process
• Gene mutation:

  (changes in a single gene)

  • either no change, change in protein structure or disruption in protein production
  • frameshift - reading frame changes
  • insertion - extra base/s inserted
  • deletion - base/s lost
  • point mutation - one base is substituted
  • missense - changes amino acid
  • silent - no change in amino acid
  • nonsense - brings amino acid to a stop
• Somatic mutations:

  • affects body cells
  • only individual affected
  • involved in cancerous growth
  • occurs most often in epithelial cells
• Germline mutation:

  • occurs in gamete cells
  • individual usually unaffected; passed onto offspring
  • affected embryos are naturally aborted (eg. PKU)'
• Chromosomal mutations: (aneuploidy)

  • duplication - section of chromosome occurs twice
  • deletion - piece of DNA removed
  • inversion - breaks occur in chromosome and broken piece joins back in the wrong way around
  • translocation - part of chromosome broken off and rejoins to wrong chromosome
  • non-disjunction - chromosome pair does not separate in meiosis → one daughter cell has an extra chromosome and other has one less
• Effect of the mutation:

  • missense - causes change in amino acid therefore in protein produced
  • nonsense - change the base sequence to the code to STOP (shorter protein produced → unlikely to function)
  • neutral - causes change in amino acid but not protein produced
  • silent - no change in amino acid
• Point mutations:

  • insertion
  • substitution
  • deletion