Difference Between Genetic Map and Physical Map

The key difference between Genetic Map and Physical Map is in the techniques used in genome mapping. When generating a genetic map, genetic markers and genetic loci are used to study the gene linkage patterns, while physical mapping uses molecular biology techniques such as Restriction Fragment Length Polymorphism (RFLP) and Hybridization techniques.

Genetic Maps and Physical maps two types of maps that construct to show the genes located in chromosomes. They involve in genetic diagnostics and to predict evolution regarding genome analysis. Furthermore, they use to analyze the distances between gene loci and to analyze gene polymorphisms.

CONTENTS

1. Overview and Key Difference
2. What is Genetic Map
3. What is Physical Map
4. Similarities Between Genetic Map and Physical Map
5. Side by Side Comparison – Genetic Map vs Physical Map in Tabular Form
6. Summary

What is Genetic Map?

A genetic map bases on the gene loci locations and genetic markers identified by linkage analysis and gene association studies. Mendelian genetics explains the genetic maps and Gregor Mendel is the person who introduced this concept. A genetic map is useful in studying the chromosome locations and the genes involved in giving rise to particular traits. These genes inherited by the daughter generations are then identified as genetic markers for a particular disease or a character.

Multiple breeding techniques over many generations and then analyzing the breeding patterns for a particular trait or characteristic are necessary before constructing a genetic map. And also, gene association studies further support the identification of different alleles which are responsible for specific inheritance patterns in genetic mapping. The allele frequencies and gene frequencies help to predict the gene map of a particular gene on a chromosome.

What is Physical Map?

Physical Maps of genes construct using the molecular biological techniques such as restriction enzyme digestion, etc. Hence, restriction map is another name for this map. When generating a physical map, in the beginning, restriction enzymes cut the DNA into fragments. These fragments then separate by gel electrophoresis. Next step is the generation of the physical map of the DNA. As a further step, they can be subjected to blotting techniques following the hybridization. At present, high throughput techniques such as Fluorescence In situ hybridization are in use, in generating physical maps to use as genetic markers.

Physical maps are more accurate and rapid with comparison to genetic maps. Hence, their use in analyzing gene polymorphism is high in comparison with genetic maps. Physical mapping does not consider Mendelian genetic patterns as well.

What are the Similarities Between Genetic Map and Physical Map?

• Both maps involve in characterizing genetic markers.
• Genome-wide studies make use of both maps.
• Genetic map and physical map are useful in genetic diagnostics.

What is the Difference Between Genetic Map and Physical Map?

Genetic Map is a gene map based on the gene linkage and gene association studies done on a genetic marker or gene loci of a chromosome. Physical map is a gene map in which the gene map is physically derived by isolating the DNA and obtaining the precise genetic marker using molecular biology techniques. With regard to the techniques used in these two maps, the difference between genetic map and physical map is that the genetic map uses gene linkage and gene association analysis methods while physical map uses restriction mapping and hybridization techniques. Therefore, the accuracy in genetic map is low while is it high in physical map.

When comparing the rapidness in the techniques used in these two maps, genetic map has less rapid, time-consuming techniques. However, physical map has very rapid techniques. Consequently, genetic map is less efficient while the physical map is highly efficient. Furthermore, genetic maps are based on Mendelian inheritance patterns whereas physical maps are not directly on Mendelian inheritance patterns.

Summary – Genetic Map vs Physical Map

Genome studies use genetic markers located in the chromosomes. To study these markers, they have to be mapped using different techniques. Mendelian genetics is the basis of genetic maps. During the genetic mapping, different traits are studied for many generations and the genes are analyzed using gene linkage and gene association studies. In contrast, Physical gene maps involve the isolation and characterization of genetic markers physically by extracting it. This is the main difference between genetic map and physical map.

Reference:

1.O’Rourke, Jamie A. “Genetic and Physical Map Correlation.” Encyclopedia of Life Sciences, Nov. 2014. Available here   
2.“Genetic Mapping Fact Sheet.” National Human Genome Research Institute (NHGRI). Available here 

Image Courtesy:

1.’File:NHGRI Fact Sheet- Genetic Mapping (27058469495)’By National Human Genome Research Institute (NHGRI) from Bethesda, MD, USA – NHGRI Fact Sheet: Genetic Mapping, (CC BY 2.0) via Commons Wikimedia 
2.’Human chromosome Y – 400 550 850 bphs’By National Center for Biotechnology Information, U.S. National Library of Medicine (Public Domain) via Commons Wikimedia