What is genome mapping?

By Emily Farthing, Freelancer writer and editor.

Genome mapping is used to identify and record the location of genes and the distances between genes on a chromosome. 

  • A genome map highlights the key ‘landmarks’ in an organism’s genome.
  • It’s not a final product, but rather a work in progress helping scientists to navigate their way around the genome as they sequence it.
  • Genome mapping provided a critical starting point for the Human Genome Project.


How do you map a genome?


  • A bit like how a map shows different landmarks to help you get around a city, a genome map helps scientists to navigate their way around the genome.
  • The landmarks on a genome map may include short DNA sequences, regulatory sites that turn genes on and off or the genes themselves.
  • Sequenced DNA fragments can be aligned to the genome map to aid with the assembly of the genome. It’s a work in progress and over time, as scientists learn more about a particular genome, the map becomes more accurate and detailed.
  • Genome mapping provided the basis for whole genome sequencing and the Human Genome Project.


Different types of genome mapping


  • There are two general types of genome mapping: genetic mapping and physical mapping.
  • Both guide scientists towards the location of a gene (or section of DNA) on a chromosome.
  • However, they rely on very different information.
    • Genetic mapping looks at how genetic information is shuffled between chromosomes or between different regions in the same chromosome during meiosis (a type of cell division), in a process called recombination or ‘crossing over’.
    • Physical mapping looks at the physical distance between known DNA sequences (including genes) by working out the number of base pairs (A-T, C-G) between them.


Illustration showing the difference between the two basic ways of mapping a genome: genetic mapping and physical mapping. Image credit: Laura Olivares Boldú / Wellcome Connecting Science

Find out more about the different ways of mapping a genome here.