Prokaryotic and Eukaryotic:
Two Basic Types of Biological Cells
CLASS NOTES from Science Prof Online
Sources & Helpful Links on Biological Cells
- Bauman, R. (2005) Microbiology.Pearson Benjamin Cummings
- Park Talaro, K. (2008) Foundations in Microbiology.
Article Summary: There are only two basic types of cells, primitive prokaryotes and the more complex eukaryotes. Here are the main features that distinguish these cell types.
Prokaryotic & Eukaryotic: Two Types of Biological Cells
Features of Prokaryotes
Pro = “before”, karyon = “nucleus”
Prokaryotes are primarily distinguished by the fact that they lack the eukaryotic feature of a membrane-bound nucleus. In fact, the only membrane in prokaryotic cells is the plasma membrane--the outer boundary of the cell itself. Their genetic material is naked within the cytoplasm, ribosomes are their only type of organelle.
Modern prokaryotes, represented by the domains Archaea and Eubacteria, are single celled organisms that reproduce through binary fission, duplicating their genetic material and then essentially splitting to form two daughter cells identical to the parent. Image of a prokaryotic cell. Click here for a labeled diagram of this cell.
Features of Eukaryotes
Eu = “true”, karyon = “nucleus”
The most noticeable feature that differentiates these more complex cells from prokaryotes is the presence of a nucleus--a double membrane-bound control center separating the genetic material, DNA (deoxyribonucleic acid), from the rest of the cell. Eukaryotic cells also have an endomembrane system composed of different membrane-bound organelles that transport materials around the cell. The endomembrane system includes the rough and smooth endoplasmic reticulum, Golgi apparatus and different types of transport vesicles.
Eukaryotes also have energy producing organelles, such as mitochondria and chloroplasts, both believed to have evolved from prokaryotes that began living symbiotically within eukaryotic cells. These vital organelles are involved in metabolism and energy conversion within the cell.
Depending on the organism, eukaryotic cells can reproduce in one of several ways, including meiosis (sexual reproduction) and mitosis (cell division producing identical daughter cells). Image of generic eukaryotic animal cell. Click here for a labeled diagram of this cell. Image of generic eukaryotic plant cell. Click here for a labeled diagram of this cell.
Only a few hundred years ago it was believed that living things could spontaneously generate, moment by moment, from non-living matter. We now know better. Living things are made of cells, and cells come from other cells.
Two Basic Types of Cells
Prokaryotic cells are evolutionarily ancient. They were here first and for billions of years were the only form of life. Today most life is prokaryotic, and these cells are supremely successful. All bacteria and bacteria-like Archaea are prokaryotic organisms.
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Portions of this article originally appeared on Suite101 online magazine.
Page last updated: 5/2013
Eukaryotes can be single celled or multi-cellular organisms. Eukaryotic cells are more complex, having evolved from a prokaryote-like predecessor. Most of the living things that we are typically familiar with are composed of eukaryotic cells; animals, plants, fungi and protists.