Question

List and discuss reasons why eukaryotes appear to have much more DNA than is necessary to code for all the possible proteins they have in their cells.

Answer 1

DNA in a cell codes for genetic elements of an organism. The DNA that doesn't codes for a protein is known as junk DNA.

In prokaryotes need for compact genetic material is there and also prokaryotes are earliest organisms in the chain of evolution hence they have very less or no junk DNA.

Eukaryotes have a large part of tgeir genome as junk DNA. More of the junk DNA present in an organism, more complex an organism is. In due course of evolution most of the genes that are useful in primitive environment becomes non-functional and hence these genes constitutes the junk DNA.

This Junk DNA is evolutionary important as they perform task and functions if conditions become unfavourable.

Futher many of the genes that are functional in eukaryotic system are still not discovered and their functions are unknown, hence they are also considered as junk.

Hence for an organism to explore all the possibilities in the present environment, to become more adaptable and to become selected in evolution junk DNA is imprortant as they function to produce proteins that may be evolutionarily important and can be used in future for adaptations to changing environment.