WHY GENE DENSITY IS HIGHER IN PROKARYOTES ?
Gene density is defined as average number of genes divided by base pairs of DNA which means ratio of the number of genes and number of base pairs.
Gene density is higher in prokaryotes because they are simpler organisms. Complexity is inversely proportional to gene density. More complex organisms such as eukaryotes has lower gene density while simpler organism such as prokaryotes has higher gene density.
Therefore, we can say that “prokaryotes are less complex than eukaryotes and thus have high gene density than eukaryotes”.
CAUSES OF HIGH GENE DENSITY IN PROKARYOTES?
1) In prokaryotes, the non- coding regions are rare.
2) Repetitive DNA is not present and if present then it is in negligible number.
3) Prokaryotes are polycistronic which means multiple genes are present in a single transcript which is controlled by a single promoter.