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How to Quantify Mutation Rates

Mutation rate is the chance for the omission or changing of a nucleotide in DNA caused either by natural mistakes in DNA processing (spontaneous mutation) or by outside agents (induced mutation). It is not to be confused with mutation frequency, which is the number of mutation incidents in a given generation. The mutation rate for a given species is usually extrapolated from data, comparing the entire DNA sequences of a cross-section of species to their descendants' DNA sequences. In the lab, this is done usually by isolating a sample group of the species and allowing it to multiply for many generations.

Things You'll Need

A large sample group of a hermaphroditic species
Supplies to create safe conditions for your sample species to live and procreate in
DNA sequencing technology

Instructions

Calculating the Mutation Rate of a Species
- 1
  For the sake of simplicity, btain a sample group of a hermaphroditic species (meaning it fertilizes its own eggs and requires no partner) that procreates quickly and for which you can easily reproduce the living conditions in a lab. Caenorhabditis Elegans is a small roundworm species that fits these criteria and has been tested for its mutation rate before.
- 2
  Sequence and record the DNA of your creatures.
- 3
  Isolate as many different individuals of the species as you can manageably maintain and observe for a long period of time in conditions under which the creature is known to prosper. This is to minimize the effect of natural selection decreasing your genetic sample.
- 4
  For each generation of your species, only keep one offspring in each line.
- 5
  Allow as many generations to come and go as possible, recording exactly how many generations pass for each line.
- 6
  Take a random sampling or the entire DNA sequences of your final offspring and compare them to the original sequence. Count the number of changes.
- 7
  At the end of your experiment use the following equation to calculate the mutation rate for your species:
  
  µ = m / ( L x g x b )
  
  where:
  
  µ = mutation rate
  
  m = number of mutations observed
  
  L = number of experimental lines
  
  g = average number of generations
  
  b = number of base pairs sequenced

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