Concept of Genes, Split Genes, Exons, Introns and Complementation Test

The heritable units which are transmitted from parents to offsprings are usually referred as Genes. So, a Gene is the fundamental biological command that has a specific role in transmission of traits or characters from one generation to the next. Due to the parallel behaviour of genes to that of chromosomes, as Genes are present on the chromosomes, everyone believed that chromosomes have definite role in inheritance, before the rediscovery of Mendel's laws. But after the discovery of DNA, it was accepted by everyone that DNA acts as a carrier of genetic information. Generally, If we need a trait to be expressed phenotypically, then the gene which is responsible for that particular trait has to express at the molecular level. So one has to understand the physical and chemical nature of the gene to understand how the traits or characters expressing phenotypically. Usually, a gene has a continuous nucleotide sequence without any interruption, which codes for an amino acid or a protein but there are some other type of genes in which the nucleotide sequence is not continuous and interrupted by non-coding sequences. So the genes which have both coding and non-coding sequences are referred as Split genes. Coding sequences are called Exons and non-coding sequences called as Introns, which are normally spliced in processing of mRNA, in a split gene. Production of a normal individual from a cross between two homozygous which are effected by same defect is referred as complementation and the test that is used to determine whether the mutation is occurred in the same gene or different genes is called as Complementation Test. Here, I am giving you a brief informative note on fine structure of gene, split genes, exons, Introns and Complementation Test.