6-5.1 Introduction

Gene mapping is like preparing a road map in which markers can be considered as the various milestones of the road between which lies the genes. The development of genetic map of an organism gives a picture of arrangement of genes in their chromosomes. The maps are composed of markers that may be genes controlling visible phenotypic traits (classical markers) or molecular markers whose phenotype is revealed by using modern molecular biology techniques (e.g. DNA markers). The goal of gene mapping is to study the regulation and expression of genes.

6-5.2 Importance of Gene Mapping

•  Mapping helps in finding the inheritance of many rare genetic disorders such as cystic fibrosis, haemophilia etc.

•  It helps in understanding the expression and regulation of a commercially important trait.

•  The information generated by a map can be further utilized for marker assisted selection, generation of high quality breed of plant and animals.

 

6-5.3 Types of Gene Mapping

Gene mapping methods are divided into a) Genetic Mapping and b) Physical Mapping. In this lecture we will discuss in length about genetic mapping and briefly about physical mapping techniques.

6-5.3(a) Genetic Mapping

It uses genetic technique (such as pedigree analysis or breeding experiments) to design a map which can show the location of genes and the patterns of sequences in a genome. The basis of genetic mapping is Linkage analysis: