Question

The map distance between genes A and B is 3 units, between B and C is 10 units and between C and A is 7 units. The order of the genes in a linkage map constructed on the above data would perhaps be
i. A, B, C
ii. A, C, B
iii. B, C, A
iv. B, A, C

Answer 1

Hint: Gene mapping can be defined as a method to determine and identify either the location of a gene, the location of the gene in a chromosome or genome or to determine the distance between the genes.

Complete answer:
Within the framework of this question, the distance between the genes A and B are determined to be 3 units, the distance between B and C is 10 units and finally the distance between C and A is 7 units. Therefore, with the help of this data, the sequence of the genes can be as follows.

Therefore, the correct answer is option iv, i.e., B, A, C.
Alfred Henry Sturtevant was an American geneticist who in the year 1911 constructed the first genetic map of the chromosome. It was called the ‘linkage map’. The locus is a fixed position on a chromosome, helps to identify different species or individuals with the assistance of genetic markers. Gene mapping identifies this gene locus and the distance between genes as mentioned earlier. Gene mapping has been utilized to identify genes and their location on the chromosome that is linked to a disease transmitted from the parent to the child. Disorders such as asthma, diabetes, cancer, psychiatric conditions, and heart diseases are believed to be gene-related. These genes can be identified by scientists with the help of genetic mapping.

Note: The Human Genome Project (HGP) has developed new and better tools to identify and understand the functions of new genes. One such tool is genetic mapping which has been used to successfully identify genes responsible for causing rare, gene inherited disorders such as duchenne muscular dystrophy and cystic fibrosis.