A cell is the basic unit of structure and function for all life, and although there are many different forms of specialized cells (such as neurons, epithelial cells, muscle cells, etc.), at the most basic level cell biology there are only two true cell types — prokaryotes and eukaryotes.
There are a number Suite101 articles which present the basics of these two types of cells, including the popular articles Prokaryotic and Eukaryotic Cells and Biology of Prokaryotic and Eukaryotic Cells. However, neither of these articles include a simple, point by point comparison that Suite101 readers continue to request. Well, here it is…what you’ve all been waiting for. There is also another corresponding article featuring the differences between prokaryotic and eukaryotic cells.
Please note that this list does not contain every conceivable similarity, but rather focuses on the main features that prokaryotic from eukaryotic cells share.
Similarities between Prokaryotic and Eukaryotic Cells
Cell walls – Most prokaryotes and some eukaryotes (plants and fungi) have a cell wall; a strong structure surrounding the cell and preventing it from bursting in a hypotonic environment. However, the cell walls of prokaryotes and eukaryotes, although similar in function, are made of different types of materials.
Cytoplasm – Both prokaryotes and eukaryotes have a fluid-like matrix that fills the cell.
Cytoskeleton – Both prokaryotes and eukaryotes have a supportive cytoskeleton within the cell, although this feature was only recently discovered to occur within prokaryotes.
Extensions of the Plasma Membrane – Both prokaryotic and eukaryotic cells can have thin extensions of the plasma membrane supported by elements of the cytoskeleton, including flagella and cilia in eukaryotes and flagella, endoflagella, fimbriae and pili in prokaryotes. These extensions can function in motility (cell movement), to move materials around the outside of the cell, or to help the cell adhere to surfaces. The mechanics of how these extensions move differs between eukaryotes and prokaryotes.
Glycocalyces – There are some prokaryotes and eukaryotes that possess a glycocalyx. These sticky sugar-based structures anchor cells to each other, help cells stick to surfaces, and provide some protection. The glycocalyces of prokaryotes and eukaryotes are made of different materials. Eukaryotes that have cell walls do not have glycocalyces an, in prokaryotes, glycocalyces can be an important factor in ability of an pathogenic (bad guy) bacteria to cause disease.
Plasma membranes – Both prokaryotes and eukaryotes have this lipid bilayer surrounding that represents the boundary between the inside and outside of the cell.
Ribosomes – These little protein factories are the cell’s only non-membrane-bound organelle. Both prokayrotes and eukaryotes manufacture proteins, therefore both cell types possess ribosomes. Ribosomes are found to float freely within both cell types, but in eukaryotic cells, ribosomes also adhere to the rough endoplasmic reticulum (an organelle which prokaryotes do not possess)
Sources
Bauman, R. (2007). Microbiology with Diseases by Taxonomy. Pearson Benjamin Cummings.
Bauman, R. (2004). Microbiology. Pearson Benjamin Cummings.
Campbell, N. and Reece J. (2002). Biology, Sixth Edition. Benjamin Cummings.
For more information on cell and microbiology, see the educational science website Science Prof Online and interactive cell models at Cells Alive.
Tami Port - Tami Port is a college professor of cell and microbiology and creator of ScienceProfOnline.com, a free science education website.
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