Question

7. Two genes lie 3 Mb apart on human chromosome 2. On average, the map distance between these loci would be 3 cM. Under what circumstances might the map distance be considerably larger or smaller than 3 cM? Explain your answer.

Answer 1

The map distance can increase or decrease due to the presence of chromosomal aberrations. The chromosomal aberrations that woud change the map distance are: translocation, duplication and deletion.

There is an increase in the map distance in case translocation and duplication of the chromosome takes place.

There is a decrease in the map distance in case deletion of the chromosome takes place. In case there is deletion of a few gene between the two gene under focus there would be a decrease in the map distance.