Compare the structure of prokaryotic and eukaryotic cells. Which do you consider to be the more primitive and why?.
There are only two types of prokaryotic cell: the bacteria and the blue-green bacteria. Examples of the eukaryotic cell include animal cells, plant cells and fungi. Viruses are neither prokaryotic nor eukaryotic. During this essay I will explore the structure of both the prokaryote and the eukaryote, and consider which is the more primitive. I will also try to explain how I reach my conclusions.
The cell is the fundamental unit of life. The first kind of life on earth was more than likely in the form of the prokaryotic cell. All cells are self sufficient units and are self contained. Surrounded by a cell membrane and containing a nucleus (or having contained a nucleus at some stage of their existence), they usually range from 10-30m in size. Eukaryotic cells are, on average, 1000 - 10000 times the volume of prokaryotic cells. Eukaryotes arose from prokaryotes, approximately 2500 million years afterwards, 1000 million years ago.
The major difference between the two types of cell is that unlike eukaryotic cells, prokaryotic cells lack membrane-bound organelles, and also a cytoskeleton. In addition to its role as structural support for the interior of the cell, the cytoskeleton is involved in intracellular organelle transport. Since there are no organelles to be transported in prokaryotic cells, this function is unnecessary. This would suggest prokaryotes as the more primitive cell.
Prokaryotic cells contain a single compartment enclosed within the cell membrane. There are no chromosomes and so the circular DNA is found free in the cytoplasm. In contrast, in eukaryotes, the DNA is located on the chromosomes, and is contained within the nucleus. This again would suggest prokaryotic cells as the more primitive.
Like the eukaryotic cell, the prokaryotic cell is filled with cytosol. The prokaryote cytosol is filled with enzymes, which carry out respiratory processes.
