announcement

Update: Check new design of our homepage!

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.
BiologyWise Staff
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
Prokaryote diagram
Sketch by Abhishek Sharma
Eukaryote diagram
Sketch by Abhishek Sharma
Cell Characteristics Prokaryotic Cells Eukaryotic Cells
Featured in organisms Domain Bacteria and Archae plants, animals, fungi, algae, protozoans
Origin 3.5 billion years ago 1.5 billion years ago
Size of the cell 0.5 micrometer in diameter or may be less 5 micrometer in diameter or more
Cell number Single-celled Multicellular
Nucleus-brain of the cell Absent Present
Nuclear membrane or Nucleolus Absent Nucleus 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 Nucleoid DNA is linear and bound by nuclear membrane
Plasma Membrane or Cytoplasmic Membrane or Outer Membrane (phospholipid bilayer) Lacks sterols Consists of sterols and carbohydrates
Chromosomes Contain Histone-like proteins Contain Histone proteins
Reproduction By binary fission Mitotic and meioitic division seen
Zygote Is partially diploid (merozygotic) Is diploid
Cell wall Contains peptidoglycan Animal cells lack cell wall. Others have either cellulose or chitin
Capsules-slimy coverings Present in bacterial cells Absent
Ribosomes 70S type 80S type. Though mitochondria and plastids have 70S type
Mitochondria Absent Present
Chloroplast Absent Present in plants
Endoplasmic Reticulum Absent Present
Golgi apparatus Absent Present
Gas vacuoles May be present Present
Membrane vacuoles Absent Present
Centrioles Absent Present
Lysosymes Absent Present
Peroxisomes Absent Present
Mesosomes May be present Absent
Endocytosis and Exocytosis Absent Present
Locomotary organ Flagella present which are made up of less number of fibrils and do not show (9+2) microtubule arrangement Flagella and pili present which have complex mechanisms and show microtubule arrangement (9+2)
Energy yielding mechanisms (Electron transport chain) Occurs in cytoplasmic membrane Occurs 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.