Prokaryotic Vs. Eukaryotic Cells

Prokaryotic Vs. Eukaryotic Cells
The basic and smallest unit of life is a cell. This article gives information about the differences between prokaryotic and eukaryotic cells.
The oldest known multicellular eukaryote is believed to be Grypania spiralis, whose fossil dates back to about 2.1 billion years. It can be found as thin films of carbon in Negaunee iron formation at the Empire Mine near Ishpeming, Michigan.
Cells have been broadly classified as: prokaryotic cells and eukaryotic cells. These terms come from the Greek word "karyon" which means "nucleus". This nucleus is considered as the brain of the cell, which directs it properly. "Pro" means "before" and "eu" means "true".

Thus, prokaryotic cells do not have a nucleus and are supposed to be primitive in nature, while the eukaryotic cells have evolved from the former ones, and show the presence of a nucleus.

Difference Between Prokaryotic and Eukaryotic Cells

Labeled Prokaryote Cell Diagram Labeled Eukaryotic Cell Diagram

Sketch by Abhishek Sharma

Cell CharacteristicsProkaryotic CellsEukaryotic Cells
Featured in organismsDomain Bacteria and Archaeplants, animals, fungi, algae, protozoans
Origin3.5 billion years ago1.5 billion years ago
Size of the cell0.5 micrometer in diameter or may be less5 micrometer in diameter or more
Cell numberSingle-celledMulticellular
Nucleus-brain of the cellAbsentPresent
Nuclear membrane or NucleolusAbsentNucleus enclosed within the Nuclear membrane
The genetic material-Deoxyribonucleic acid(DNA)DNA is freely floating and circular, not bound by the nuclear membrane, popularly called NucleoidDNA is linear and bound by nuclear membrane
Plasma Membrane or Cytoplasmic Membrane or Outer Membrane (phospholipid bilayer)Lacks sterolsConsists of sterols and carbohydrates
ChromosomesContain Histone-like proteinsContain Histone proteins
ReproductionBy binary fissionMitotic and meioitic division seen
ZygoteIs partially diploid (merozygotic)Is diploid
Cell wallContains peptidoglycanAnimal cells lack cell wall. Others have either cellulose or chitin
Capsules-slimy coveringsPresent in bacterial cellsAbsent
Ribosomes70S type80S type. Though mitochondria and plastids have 70S type
ChloroplastAbsentPresent in plants
Endoplasmic ReticulumAbsentPresent
Golgi apparatusAbsentPresent
Gas vacuolesMay be presentPresent
Membrane vacuolesAbsentPresent
MesosomesMay be presentAbsent
Endocytosis and ExocytosisAbsentPresent
Locomotary organFlagella present which are made up of less number of fibrils and do not show (9+2) microtubule arrangementFlagella and pili present which have complex mechanisms and show microtubule arrangement (9+2)
Energy yielding mechanisms (Electron transport chain)Occurs in cytoplasmic membraneOccurs in mitochondrial membrane by glycolysis cycle

As evident till now, all living beings are made up of cells and cell products, consisting of a number of cell organelles, which help in carrying out various life processes. A matter of debate between prokaryotic and eukaryotic cells is mitochondria - the energy-yielding organelle, which is supposed to be independent. They have their own genetic material - the DNA and hence, are capable of division. They have a symbiotic sort of relationship with the cell in which they reside. Thus, it might be obvious that they have originated from a single independent prokaryotic unit, since they are similar to them, in the sense that they have an unbound circular DNA. But the surprising thing is that the prokaryotic units lack mitochondria. Does this mean that it is a living organism residing inside another cell, or is it just an independent organ? If you are aware of all the scientific terms used, it will be easy to grasp.