Genetic mapping and physical mapping are two techniques used in genome mapping. Mapping gives a relative or exact distance and location of genes on the chromosomes. There are two types of mapping – Genetic Mapping and Physical Mapping.
Genetic Mapping
Genetic Mapping is used to find out the relative position of genes in a chromosome. It uses recombination and linkage studies to find out the relative distance and inheritance pattern. The mapping begins by collecting specimens from close relatives and isolating their DNA. These DNAs are studied closely to find out the polymorphisms, which serve as our genetic marker.
The closer two genetic markers are located, more are their chances to get inherited in the next generation.
The mapping gives an idea whether the genes will undergo recombination or not. The distance is measured in centimorgans, after the scientist Thomas Hunt Morgan.
Physical Mapping
Physical mapping provides the accurate physical distance between the genetic markers in terms of nucleotides. It can be done using different techniques like restriction mapping, fluorescent in situ hybridization mapping or sequenced tag site mapping. In the restriction mapping technique, the DNA sequences are cut using restriction enzymes, then the fragments are separated by electrophoresis. The migration pattern is then used to analyze the DNA and construct the maps.
Now that we know about genetic mapping and physical mapping, let us look at their differences.
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It is a technique which shows how genetic information is shuffled in a chromosome.. |
It is a technique which shows the physical distance in a DNA sequence by working out the number of base pairs. |
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It uses genetic markers to map the distance between two genes. |
It uses restriction enzymes to cut the specific sequence of DNA. |
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It depicts the region of polymorphisms (region where the DNA sequence differs) in different individuals. |
It depicts the actual distance of base pairs along a stretch of DNA. |
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It gives mere insights for different regions of chromosomes. |
It depicts a more accurate representation of the genome. |
Conclusion
Genetic mapping and physical mapping are ongoing studies, which will advance more in the future. While genetic mapping gives the outline of a chromosome, physical mapping gives the details. Information from both the maps are combined together to study the chromosomes.
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FAQs
What are the physical mapping methods?
Physical mapping methods are restriction mapping, fluorescence in situ hybridization mapping and sequence tagged site mapping.
Why is genetic mapping important?
Genetic mapping is important because it can give relative distance between the genes on a chromosome, which is useful in recombination and linkage studies.
Who discovered gene mapping?
T.H Morgan and Alfred H Sturtevant mapped the first gene map in 1913.
What is the unit of a genetic map?
Centimorgan is the unit of a genetic map.
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