Principles of Genetics and Breeding

1.3.8 Genetic significance of chromosomes

The chromosomes are considered as the organs of heredity because of the following reasons.

• They form the only link between two generations.
• A diploid chromosome set consists of two morphologically similar (except the X and Y sex chromosomes) sets, one is derived from the mother and another from the father at fertilization.
• The genetic material, DNA or RNA is localized in the chromosome and its contents are relatively constant from one generation to the next.
• The chromosomes maintain and replicate the genetic informations contained in their DNA molecule and this information is transcribed at the right time in proper sequence into the specific types of RNA molecules which directs the synthesis of different types of proteins to form a body form like the parents.