The children acquire the characteristic features of theirs parents. The inheritance of these hereditary characters can be explained on the basis of ancestral genes that are found to be arranged on chromosomes, and they make the total genetic make-up of the organism.
But the question arises, What are gene? What are genes chemically composed of and their functions and how are they transmitted to the offspring's?
The hereditary units which are transmitted from one generation to another are called genes. It is a fundamental biological unit which is called as functional factor of heredity.
These characters are transmitted from parents to the offspring's during reproduction which forms the basis of maintaining continuity of a species. Genes responsible for transmission are located on chromosomes and through the gametes enter a diploid zygote cell which occurs in all sexually reproducing organisms. Thus, each offspring's receives 50% genes from male parent and the remaining 50% from the female parent during fusion of gametes to form zygote.
ON THE BASIS OF MODERN CONCEPT OF GENETIC KNOWLEDGE :
Genetics material of any organism is the substance that carries genetic information determining the properties of that organism. The genetic material is also responsible for transferring genetic material from parent to their offspring's.
CHARACTERISTICS OR PROPERTIES OF GENETIC MATERIAL :
Genes are linearly arranged segments of DNA molecule, which determines the inheritance and expression of particular hereditary characters. The principle criteria material should therefore:
1. Possesses the ability to store and express genetic information and also transmit as required.
2. Possesses the ability to make its own replica so that a copy of it may be transmitted to the offspring.
3. Possesses the ability to transfer its information from parent cell to daughter cells with least minimal error.
4. Maintains physical and chemical stability in order to prevent loss of genetic information.
5. Possesses the capability for genetic change without major loss of parental information which generates the biological variations essential for evolution.
