Detailed Differences Between Eukaryotic and Prokaryotic Cells

DETAILED DIFFERENCES BETWEEN EUKARYOTIC AND PROKARYOTIC CELLS

Cells are divided into two categories namely the Prokaryotes and Eukaryotes. These two have varying differences between them. Speaking in simple cell biology words, prokaryotes are primitive, simple organisms that lack membranous cell organelles. The opposite of this are eukaryotes, which are advanced and complex organisms having membrane bound cell organelles. Seemingly simple in structure and markedly different from eukaryote and protist organisms, prokaryotic cells are believed to have been amongst the first on the Earth and very well may out-survive all other organisms. Examples of prokaryotes are bacteria and archaea and eukaryotes include fungi, animal and plant cells.

One of the main differentiating points between the two is the presence or absence of membrane enclosed nuclear body. In prokaryotes, it lacks outer membrane covering and nucleolus, whereas nucleolus is present and a double layered membrane surrounds the nuclear body in eukaryotes. Referred to as cell nucleus in eukaryotes, such an organelle is called nucleoid in prokaryotes.

The nuclear body houses the chromosome in both prokaryotes and eukaryotes. Single in number and circular in shape, the chromosome in prokaryotes is made up of Deoxyribonucleic Acid (DNA) and proteins whilst in eukaryotes, it is usually more than two in number, and composed of DNA, histone and other proteins.

In terms of ribosomes prokaryotes consist of 70S type, and the two subunits are 50S and 30S. Ribosome in eukaryotes is of 80S type, and the two comprising subunits are 60S and a 40S. Since the cell size in prokaryotes is relatively smaller to that of the eukaryotes, the organelles like mitochondria, golgi bodies, endoplasmic reticulum and chloroplast are absent in the small-sized prokaryotic cells whilst Eukaryotic cells house all these membrane bound organelles inside the cell. Cell division in prokaryotes is simple, and occurs by binary fission method. Over here, the parent cell (haploid cell) divides into two equal daughter cells. Eukaryotes have diploid cell that divides first by mitosis, and further into two haploid ones by meiosis. The resulting haploid gametes fuse to give a diploid cell.

Prokaryotes are generally able to carry out their life processes of growth, energy generation and reproduction independently of other cells which is very different to the cells of eukaryotes which are unable to live alone in nature and can exist only as part of a multicellular organism. Most eukaryotic cells are uniquely suited to their own particular environmental niche and rarely grows out of it, but prokaryotes i.e. bacteria can grow in a multiplicity of environments ranging from hot sulphur springs (65°C) to deep freezers (–20°C) and also in nutritionally poor environment. A major difference in chemical composition between prokaryotic and eukaryotic cells is that eukaryotes have sterols in their membranes (e.g. cholesterol) whereas the plasma membrane of prokaryotic cells does not contain carbohydrates and generally lacks sterols. In prokaryotic cells the enzymes, topoisomerases, that control