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The Structure of Cells

Author(s): Center for Educational Outreach

Prokaryotic and Eukaryotic Cells

The basic cell unit can be one of only two types: prokaryotic or eukaryotic. 

Prokaryotes are generally smaller than eukaryotic cells. The major difference between eukaryotic and prokaryotic cells is the location of their DNA. Prokaryotic DNA is located in a central non-membrane bound region, called the nucleoid. No membrane bound organelles are present, only ribosomes that synthesize proteins. Prokaryotes have a rigid cell wall surrounding their plasma membrane. 

Protists, fungi, animals and plants consist of eukaryotic cells. Eukaryotic DNA is located in the membrane-bound nucleus. Eukaryotes also contain many membrane-bound organelles, suspended in cytoplasm, which perform specialized cellular functions. Each cell is enclosed by a cytoskeleton, made up of microtubules and filaments, that helps define the cell’s shape.