Fuctional mRNA of structural genes need not alwaus include all of its exons. This alternate splicing of exons is sex-specific, tissue-specific and even developmental stage-specific. By such alternate splicing of exons, a single gene may encode for several isoproteins and /or proteins of similar class.
Protein/isoprotein. Such an extravagancy has been avoided in naturel phenomena by way of alternate splicing.
