A centimorgan is a unit of measure used to approximate the distance between genes

  • Thomas Morgan demonstrated that genes that were further apart on a chromosome were more likely to recombine
  • This is because there are more potential sites for crossing over to occur between distant genes

One centimorgan (or genetic map unit / m. u.) is the equivalent to a recombination frequency of 1%

  • A centimorgan is not a true measure of distance and will differ in equivalence between species
  • In humans, 1 cM corresponds to approximately 1 million bp on average

While centimorgans may still be used to quantitate recombination frequencies, they are no longer used to measure distance

  • Genome mapping has allowed scientists to determine specific distances between genes in kilo bases (kb)