Plantlet The Blogging Platform of Department of Botany, University of Dhaka
Gene mapping
The diagrammatic representation of location and arrangement of genes and relative distance between linked gene of a chromosome is called linkage map or genetic map.
Unit of genetic map is Morgan or Centimorgan.
History
Test cross
Gene map distance
If the percentage of crossing over between two linked gene is 1%, then the map distance between linked gene will be 1 M.
The probability of crossing over between two genes is directly proportional to distance between them.
When two genes are nearer, the probability of crossing over between them is limited.
The probability of making a random cut between the two knots/genes is proportional to the distance between them.
Every cut separates A from E whereas 5/100 cut only separates C from D.
Uses of gene mapping-
- Useful to determine the location, arrangement and linkage of genes in a chromosome.
- Useful to predict the result of dihybrid and trihybrid crosses.
Two point test cross in Drosophilla
Map distance
What is 3 point cross
3 point cross in Drosophila
