Prokaryotes and Eukaryotes

Cells come in a variety of shapes and sizes. Despite their differences, all cells have two characteristics in common: they are surrounded by a membrane and they contain DNA.

Cells fall into two broad categories, depending on whether or not they contain a nucleus:

The two types of cells:

Prokaryotes

Examples:

Unicellular

Individuals are unicellular, but can appear in groups (chains or clusters)

Very small and simple
DNA is contained in the nucleoid
Enclosed by a plasma membrane

Most prokaryotes have a cell wall too.
The cell wall of bacteria contains peptidoglycan

Eukaryotes

Examples:

Animals
Plants
Fungi
Protists
Protozoa

Unicellular or Multicellular
DNA is contained in the nucleus
Eukaryotic cells can be up to 10 times larger than prokaryotic cells
Have membrane bound compartments: organelles

Below is a comparison between prokaryotes and the eukaryotes.

	Prokaryotes	Eukaryotes
Word Root	Pre-nucleus	True-nucleus
Evolutionary Age	Believed to be older	Believe to be younger
Membrane bound organelles	Normally absent	Present
Nucleoli	Absent	Present
Nuclear membrane	Absent	Present
Chromosomes	Single loop of DNA and no histones	Multiple chromosomes containing DNA and histones
Capsule	Present in many prokaryotes	Quite rare in eukaryotes. Example: some fungi
Cell wall	Normally present	Present in algae, fungi and plants
Ribosomes	70S	80S (also 70S in some organelles)
Cell division	Binary fission	Mitosis
Organisms	Only Archaea and Bacteria	Animals, plants, fungi, protests, protozoa

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