Prokaryotes were the only form of life on Earth for millions of years until more complicated eukaryotic cells came into being through the process of evolution.
Prokaryotes also differ from eukaryotes in the structure, packing, density, and arrangement of their genes on the chromosome. Prokaryotes have incredibly compact genomes compared to eukaryotes, mostly because prokaryote genes lack introns and large non-coding regions between each gene. Whereas nearly 95% of the human genome does not code for proteins or RNA or includes a gene promoter, nearly all of the prokaryote genome codes or controls something. n a prokaryote cell, all genes in an operon(three in the case of the famous lac operon) are transcribed on the same piece of RNA and then made into separate proteins, whereas if these genes were native to eukaryotes, they each would have their own promoter and be transcribed on their own strand of mRNA. This lesser degree of control over gene expression contributes to the simplicity of the prokaryotes as compared to the eukaryotes. All cellular organism fall into two natural groups, known as prokaryotes and eukaryotes. These two groups are fundamentally different. The terms prokaryote and eukaryote refer to the differences in the location of the DNA. In prokaryotes the DNA is not enclosed by nuclear membranes and lies free in the cytoplasm. The cells therefore lack true nuclei . The cells of eukaryotes, however, do contain true nuclei.
Eukaryotes arose around 1.2 thousand million years ago, and they evolved from prokaryotes which began around 3.5 thousand