Genetic material is a chemical substance that constitutes the genes, controlling expression and inheritance of traits. There are two candidates for forming the genetic material, proteins and nucleic acids. Proteins have innumerable variety because of their being formed from 20 amino acids. However, they have no mechanism of replication.
The other candidate is DNA. It has the requisite ability to replicate a transcribe chemicals for controlling metabolism. Experiment of Hershey and Chase (1952) unequally proved that DNA is genetic material. However, it was soon discovered that in several viruses, RNA is genetic material, e.g., HIV, Tobacco Mosaic Virus. Outside viruses, the genetic material is exclusively made of DNA. Here, RNA functions as a messenger, an adapter and protein assembly point.
Requirements of Genetic Material
1. Genetic Information. It should contain all the genetic information in coded form.
2. Ubiquity. Genetic material must be present in various forms of life. All the cells of multicellular organisms which possess totipotency or pluripotency must have the same.
3. Amount. Amount of genetic material should be same in all cells of the body.
4. Diversity. It should have the diversity corresponding to the diversity found in organisms and the variations found in them.
5. Replication. The genetic material should be able to form its replicas which are transferred to progeny.
6. Controls. There is an intrinsic system of controls which provide for differential expression of genetic material depending upon the state of development, location and functioning.
7. Stability. It should not be highly reactive but must be chemically and structurally stable.
8. Expression. The genetic material should have a system to express itself in the form of Mendelian characters.
9. Mutations. It should be able to undergo slow changes or mutations which are essential for adatability and evolution.
