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The below mentioned article will highlight the characteristics of genetic material and eight properties of DNA in genetic material.
Characteristics of Genetic Material:
The following are the properties and functions which should be fulfilled by a substance if it has to qualify as genetic material:
1. It should be present in every cell.
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2. It must contain all the biologically useful information in a stable form.
3. It should be able to store information in the coded form for the control of biological functions of the cells, and also to express its information.
4. It should show diversity corresponding to the variety existing in the organisms.
5. It should be able to replicate precisely, and then faithfully pass over its true copies to the successive generation.
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6. It should also be capable of variations, i.e., recombination and mutation. Further, such variations must be stable and inheritable.
7. The genetic material should be able to generate its own kind and also new kinds of molecules.
8. It should be capable of differential expression so that the various parts of an organism may acquire specific form, structure and functions in-spite of having the same genetic material.
Obviously, one would look for a macromolecule to satisfy the complex functions of genetic material present in the genes. Originally the proteins were thought to play the role of genetic material because they show enormous variety due to various combinations of their 20 constituent amino acids. However, they have no mechanism for replication (i.e., duplication), which is the most important feature of genetic material.
Hence, they do not qualify to act as the genetic material. However, it turned out on the basis of experimental evidences that DNA (Deoxyribonucleic Acid) is the genetic material. DNA shows a wide structural variety because the four types of nucleotide units it is composed of may be arranged in an endless manner in its molecules. It also fulfills all the requirements of the genetic material mentioned above.
Properties of DNA in Genetic Material:
The following properties of DNA, present in all the cells of organisms, amply prove that it is genetic material:
1. It is present in all the cells of organisms. Each somatic cell of given species possesses double the amount of DNA than what is present in its gametes.
2. It shows a extremely wide variety due to unlimited sequences in which its monomers can exist.
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3. It replicates precisely during interphase of the cell division, and its copies possessing genetic information are very faithfully transmitted to the daughter cells, representing successive generation, during mitosis.
4. Occasionally, it also produces mutations in the genes.
5. DNA stores genetic information as a ‘triplet code’ and expresses its genetic information by transcription of mRNA and synthesis of proteins. These proteins not only control the structure of the cells, but also control their metabolic activities by acting as enzymes.
6. Genes, composed of DNA, show differential gene activity that is responsible for the process of differentiation in the organism. In other words, different genes remain functional in different cell types so that the latter may acquire their specific structure and functions.
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7. DNA, if damaged, can repair itself so as to preserve genetic information present in it.
8. DNA absorbs the same wavelengths of high-energy radiations that can cause maximum mutation (inheritable variation).
